diff --git a/toolchain/check/handle_parameter_list.cpp b/toolchain/check/handle_parameter_list.cpp
index 100364a5543d..ab71f44a35ce 100644
--- a/toolchain/check/handle_parameter_list.cpp
+++ b/toolchain/check/handle_parameter_list.cpp
@@ -6,14 +6,14 @@
 
 namespace Carbon::Check {
 
-auto HandleDeducedParameterList(Context& context, Parse::Node parse_node)
+auto HandleImplicitParameterList(Context& context, Parse::Node parse_node)
     -> bool {
-  return context.TODO(parse_node, "HandleDeducedParameterList");
+  return context.TODO(parse_node, "HandleImplicitParameterList");
 }
 
-auto HandleDeducedParameterListStart(Context& context, Parse::Node parse_node)
+auto HandleImplicitParameterListStart(Context& context, Parse::Node parse_node)
     -> bool {
-  return context.TODO(parse_node, "HandleDeducedParameterListStart");
+  return context.TODO(parse_node, "HandleImplicitParameterListStart");
 }
 
 auto HandleParameterList(Context& context, Parse::Node parse_node) -> bool {
diff --git a/toolchain/diagnostics/diagnostic_kind.def b/toolchain/diagnostics/diagnostic_kind.def
index 1e76d7c7ed5b..c60887593e6c 100644
--- a/toolchain/diagnostics/diagnostic_kind.def
+++ b/toolchain/diagnostics/diagnostic_kind.def
@@ -100,8 +100,8 @@ CARBON_DIAGNOSTIC_KIND(ExpectedDeclarationSemi)
 CARBON_DIAGNOSTIC_KIND(ExpectedDeclarationSemiOrDefinition)
 CARBON_DIAGNOSTIC_KIND(ExpectedInitializerAfterLet)
 CARBON_DIAGNOSTIC_KIND(MethodImplNotAllowed)
+CARBON_DIAGNOSTIC_KIND(ParametersRequiredAfterImplicit)
 CARBON_DIAGNOSTIC_KIND(ParametersRequiredByIntroducer)
-CARBON_DIAGNOSTIC_KIND(ParametersRequiredByDeduced)
 
 // ============================================================================
 // Semantics diagnostics
diff --git a/toolchain/parse/context.h b/toolchain/parse/context.h
index 008c401e8d08..be7db8040e12 100644
--- a/toolchain/parse/context.h
+++ b/toolchain/parse/context.h
@@ -30,7 +30,7 @@ class Context {
 
   // Supported kinds for HandlePattern.
   enum class PatternKind : int8_t {
-    DeducedParameter,
+    ImplicitParameter,
     Parameter,
     Variable,
     Let
diff --git a/toolchain/parse/handle_declaration_name_and_params.cpp b/toolchain/parse/handle_declaration_name_and_params.cpp
index c3f9cb5aa890..4b24a26636cb 100644
--- a/toolchain/parse/handle_declaration_name_and_params.cpp
+++ b/toolchain/parse/handle_declaration_name_and_params.cpp
@@ -82,8 +82,8 @@ static auto HandleDeclarationNameAndParamsAfterName(Context& context,
   }
 
   if (context.PositionIs(Lex::TokenKind::OpenSquareBracket)) {
-    context.PushState(State::DeclarationNameAndParamsAfterDeduced);
-    context.PushState(State::ParameterListAsDeduced);
+    context.PushState(State::DeclarationNameAndParamsAfterImplicit);
+    context.PushState(State::ParameterListAsImplicit);
   } else if (context.PositionIs(Lex::TokenKind::OpenParen)) {
     context.PushState(State::ParameterListAsRegular);
   } else if (params == Params::Required) {
@@ -109,16 +109,17 @@ auto HandleDeclarationNameAndParamsAfterNameAsRequired(Context& context)
   HandleDeclarationNameAndParamsAfterName(context, Params::Required);
 }
 
-auto HandleDeclarationNameAndParamsAfterDeduced(Context& context) -> void {
+auto HandleDeclarationNameAndParamsAfterImplicit(Context& context) -> void {
   context.PopAndDiscardState();
 
   if (context.PositionIs(Lex::TokenKind::OpenParen)) {
     context.PushState(State::ParameterListAsRegular);
   } else {
     CARBON_DIAGNOSTIC(
-        ParametersRequiredByDeduced, Error,
-        "A `(` for parameters is required after deduced parameters.");
-    context.emitter().Emit(*context.position(), ParametersRequiredByDeduced);
+        ParametersRequiredAfterImplicit, Error,
+        "A `(` for parameters is required after implicit parameters.");
+    context.emitter().Emit(*context.position(),
+                           ParametersRequiredAfterImplicit);
     context.ReturnErrorOnState();
   }
 }
diff --git a/toolchain/parse/handle_parameter.cpp b/toolchain/parse/handle_parameter.cpp
index 69d2bb80321f..abdc3114e425 100644
--- a/toolchain/parse/handle_parameter.cpp
+++ b/toolchain/parse/handle_parameter.cpp
@@ -6,7 +6,7 @@
 
 namespace Carbon::Parse {
 
-// Handles ParameterAs(Deduced|Regular).
+// Handles ParameterAs(Implicit|Regular).
 static auto HandleParameter(Context& context, State pattern_state,
                             State finish_state) -> void {
   context.PopAndDiscardState();
@@ -15,9 +15,9 @@ static auto HandleParameter(Context& context, State pattern_state,
   context.PushState(pattern_state);
 }
 
-auto HandleParameterAsDeduced(Context& context) -> void {
-  HandleParameter(context, State::PatternAsDeducedParameter,
-                  State::ParameterFinishAsDeduced);
+auto HandleParameterAsImplicit(Context& context) -> void {
+  HandleParameter(context, State::PatternAsImplicitParameter,
+                  State::ParameterFinishAsImplicit);
 }
 
 auto HandleParameterAsRegular(Context& context) -> void {
@@ -25,7 +25,7 @@ auto HandleParameterAsRegular(Context& context) -> void {
                   State::ParameterFinishAsRegular);
 }
 
-// Handles ParameterFinishAs(Deduced|Regular).
+// Handles ParameterFinishAs(Implicit|Regular).
 static auto HandleParameterFinish(Context& context, Lex::TokenKind close_token,
                                   State param_state) -> void {
   auto state = context.PopState();
@@ -41,9 +41,9 @@ static auto HandleParameterFinish(Context& context, Lex::TokenKind close_token,
   }
 }
 
-auto HandleParameterFinishAsDeduced(Context& context) -> void {
+auto HandleParameterFinishAsImplicit(Context& context) -> void {
   HandleParameterFinish(context, Lex::TokenKind::CloseSquareBracket,
-                        State::ParameterAsDeduced);
+                        State::ParameterAsImplicit);
 }
 
 auto HandleParameterFinishAsRegular(Context& context) -> void {
@@ -51,7 +51,7 @@ auto HandleParameterFinishAsRegular(Context& context) -> void {
                         State::ParameterAsRegular);
 }
 
-// Handles ParameterListAs(Deduced|Regular).
+// Handles ParameterListAs(Implicit|Regular).
 static auto HandleParameterList(Context& context, NodeKind parse_node_kind,
                                 Lex::TokenKind open_token_kind,
                                 Lex::TokenKind close_token_kind,
@@ -66,11 +66,11 @@ static auto HandleParameterList(Context& context, NodeKind parse_node_kind,
   }
 }
 
-auto HandleParameterListAsDeduced(Context& context) -> void {
+auto HandleParameterListAsImplicit(Context& context) -> void {
   HandleParameterList(
-      context, NodeKind::DeducedParameterListStart,
+      context, NodeKind::ImplicitParameterListStart,
       Lex::TokenKind::OpenSquareBracket, Lex::TokenKind::CloseSquareBracket,
-      State::ParameterAsDeduced, State::ParameterListFinishAsDeduced);
+      State::ParameterAsImplicit, State::ParameterListFinishAsImplicit);
 }
 
 auto HandleParameterListAsRegular(Context& context) -> void {
@@ -80,7 +80,7 @@ auto HandleParameterListAsRegular(Context& context) -> void {
                       State::ParameterListFinishAsRegular);
 }
 
-// Handles ParameterListFinishAs(Deduced|Regular).
+// Handles ParameterListFinishAs(Implicit|Regular).
 static auto HandleParameterListFinish(Context& context,
                                       NodeKind parse_node_kind,
                                       Lex::TokenKind token_kind) -> void {
@@ -90,8 +90,8 @@ static auto HandleParameterListFinish(Context& context,
                   state.subtree_start, state.has_error);
 }
 
-auto HandleParameterListFinishAsDeduced(Context& context) -> void {
-  HandleParameterListFinish(context, NodeKind::DeducedParameterList,
+auto HandleParameterListFinishAsImplicit(Context& context) -> void {
+  HandleParameterListFinish(context, NodeKind::ImplicitParameterList,
                             Lex::TokenKind::CloseSquareBracket);
 }
 
diff --git a/toolchain/parse/handle_pattern.cpp b/toolchain/parse/handle_pattern.cpp
index d09125d15388..be0f658c9e89 100644
--- a/toolchain/parse/handle_pattern.cpp
+++ b/toolchain/parse/handle_pattern.cpp
@@ -6,7 +6,7 @@
 
 namespace Carbon::Parse {
 
-// Handles PatternAs(DeducedParameter|FunctionParameter|Variable|Let).
+// Handles PatternAs(ImplicitParameter|FunctionParameter|Variable|Let).
 static auto HandlePattern(Context& context, Context::PatternKind pattern_kind)
     -> void {
   auto state = context.PopState();
@@ -23,7 +23,7 @@ static auto HandlePattern(Context& context, Context::PatternKind pattern_kind)
   // Handle an invalid pattern introducer for parameters and variables.
   auto on_error = [&]() {
     switch (pattern_kind) {
-      case Context::PatternKind::DeducedParameter:
+      case Context::PatternKind::ImplicitParameter:
       case Context::PatternKind::Parameter: {
         CARBON_DIAGNOSTIC(ExpectedParameterName, Error,
                           "Expected parameter declaration.");
@@ -51,12 +51,13 @@ static auto HandlePattern(Context& context, Context::PatternKind pattern_kind)
     context.PushState(state);
   };
 
-  // The first item should be an identifier or, for deduced parameters, `self`.
+  // The first item should be an identifier or, in an implicit parameter list,
+  // `self`.
   bool has_name = false;
   if (auto identifier = context.ConsumeIf(Lex::TokenKind::Identifier)) {
     context.AddLeafNode(NodeKind::Name, *identifier);
     has_name = true;
-  } else if (pattern_kind == Context::PatternKind::DeducedParameter) {
+  } else if (pattern_kind == Context::PatternKind::ImplicitParameter) {
     if (auto self = context.ConsumeIf(Lex::TokenKind::SelfValueIdentifier)) {
       context.AddLeafNode(NodeKind::SelfValueName, *self);
       has_name = true;
@@ -84,8 +85,8 @@ static auto HandlePattern(Context& context, Context::PatternKind pattern_kind)
   }
 }
 
-auto HandlePatternAsDeducedParameter(Context& context) -> void {
-  HandlePattern(context, Context::PatternKind::DeducedParameter);
+auto HandlePatternAsImplicitParameter(Context& context) -> void {
+  HandlePattern(context, Context::PatternKind::ImplicitParameter);
 }
 
 auto HandlePatternAsParameter(Context& context) -> void {
diff --git a/toolchain/parse/node_kind.def b/toolchain/parse/node_kind.def
index ccadf025a9db..68d8e56410de 100644
--- a/toolchain/parse/node_kind.def
+++ b/toolchain/parse/node_kind.def
@@ -148,22 +148,22 @@ CARBON_PARSE_NODE_KIND_BRACKET(FunctionDeclaration, FunctionIntroducer,
                                CARBON_TOKEN(Semi)
                                    CARBON_IF_ERROR(CARBON_TOKEN(Fn)))
 
-// A parameter list, possibly deduced:
-//   [Deduced]ParamertListStart
+// A parameter list, possibly implicit:
+//   [Implicit]ParamertListStart
 //   _external_: [Generic]PatternBinding
 //   ParameterListComma
-// [Deduced]ParameterList
+// [Implicit]ParameterList
 //
 // Expressions and ParameterListComma may repeat with ParameterListComma as a
 // separator.
 CARBON_PARSE_NODE_KIND_CHILD_COUNT(ParameterListStart, 0,
                                    CARBON_TOKEN(OpenParen))
-CARBON_PARSE_NODE_KIND_CHILD_COUNT(DeducedParameterListStart, 0,
+CARBON_PARSE_NODE_KIND_CHILD_COUNT(ImplicitParameterListStart, 0,
                                    CARBON_TOKEN(OpenSquareBracket))
 CARBON_PARSE_NODE_KIND_CHILD_COUNT(ParameterListComma, 0, CARBON_TOKEN(Comma))
 CARBON_PARSE_NODE_KIND_BRACKET(ParameterList, ParameterListStart,
                                CARBON_TOKEN(CloseParen))
-CARBON_PARSE_NODE_KIND_BRACKET(DeducedParameterList, DeducedParameterListStart,
+CARBON_PARSE_NODE_KIND_BRACKET(ImplicitParameterList, ImplicitParameterListStart,
                                CARBON_TOKEN(CloseSquareBracket))
 
 // An array type, such as  `[i32; 3]` or `[i32;]`:
diff --git a/toolchain/parse/state.def b/toolchain/parse/state.def
index 71ba51a4a5cb..0829e0a09a80 100644
--- a/toolchain/parse/state.def
+++ b/toolchain/parse/state.def
@@ -179,10 +179,9 @@ CARBON_PARSE_STATE(CodeBlockFinish)
 //   2. PeriodAsDeclaration
 // Else:
 //   (state done)
-CARBON_PARSE_STATE_VARIANTS3(DeclarationNameAndParams, None, Optional,
-                              Required)
+CARBON_PARSE_STATE_VARIANTS3(DeclarationNameAndParams, None, Optional, Required)
 
-// Handles a declaration name between the main name and deduced parameters.
+// Handles a declaration name between the main name and implicit parameters.
 //
 // For `None`, parameters aren't supported so only `Period` or `Else` paths are
 // used.
@@ -191,23 +190,23 @@ CARBON_PARSE_STATE_VARIANTS3(DeclarationNameAndParams, None, Optional,
 //   1. DeclarationNameAndParamsAfterNameAs(None|Optional|Required)
 //   2. PeriodAsDeclaration
 // If `OpenSquareBracket`:
-//   1. ParameterListAsDeduced
-//   2. DeclarationNameAndParamsAfterDeduced
+//   1. ParameterListAsImplicit
+//   2. DeclarationNameAndParamsAfterImplicit
 // If `OpenParen`:
 //   1. ParameterListAsRegular
 // Else:
 //   (state done)
 CARBON_PARSE_STATE_VARIANTS3(DeclarationNameAndParamsAfterName, None, Optional,
-                              Required)
+                             Required)
 
 // Handles regular parameters such as `(...)` for the general declaration case.
-// Only used after deduced parameters.
+// Only used after implicit parameters.
 //
 // If `OpenParen`:
 //   1. ParameterListAsRegular
 // Else:
 //   (state done)
-CARBON_PARSE_STATE(DeclarationNameAndParamsAfterDeduced)
+CARBON_PARSE_STATE(DeclarationNameAndParamsAfterImplicit)
 
 // Handles processing of a declaration scope. Things like fn, class, interface,
 // and so on.
@@ -439,36 +438,36 @@ CARBON_PARSE_STATE(NamespaceFinish)
 //   (state done)
 CARBON_PARSE_STATE(Package)
 
-// Starts deduced parameter processing.
+// Starts implicit parameter processing.
 //
 // Always:
-//   1. PatternAs(DeducedParameter|Parameter)
-//   2. ParameterFinishAs(Deduced|Regular)
-CARBON_PARSE_STATE_VARIANTS2(Parameter, Deduced, Regular)
+//   1. PatternAs(ImplicitParameter|Parameter)
+//   2. ParameterFinishAs(Implicit|Regular)
+CARBON_PARSE_STATE_VARIANTS2(Parameter, Implicit, Regular)
 
-// Finishes deduced parameter processing, including `,`. If there are more
+// Finishes implicit parameter processing, including `,`. If there are more
 // parameters, enqueues another parameter processing state.
 //
 // If `Comma` without the list close token:
-//   1. ParameterAs(Deduced|Regular)
+//   1. ParameterAs(Implicit|Regular)
 // Else:
 //   (state done)
-CARBON_PARSE_STATE_VARIANTS2(ParameterFinish, Deduced, Regular)
+CARBON_PARSE_STATE_VARIANTS2(ParameterFinish, Implicit, Regular)
 
 // Handles processing of a parameter list `[` or `(`.
 //
 // If the list close token:
-//   1. ParameterListFinishAs(Deduced|Regular)
+//   1. ParameterListFinishAs(Implicit|Regular)
 // Else:
-//   1. ParameterAs(Deduced|Regular)
-//   2. ParameterListFinishAs(Deduced|Regular)
-CARBON_PARSE_STATE_VARIANTS2(ParameterList, Deduced, Regular)
+//   1. ParameterAs(Implicit|Regular)
+//   2. ParameterListFinishAs(Implicit|Regular)
+CARBON_PARSE_STATE_VARIANTS2(ParameterList, Implicit, Regular)
 
 // Handles processing of a parameter list `]` or `)`.
 //
 // Always:
 //   (state done)
-CARBON_PARSE_STATE_VARIANTS2(ParameterListFinish, Deduced, Regular)
+CARBON_PARSE_STATE_VARIANTS2(ParameterListFinish, Implicit, Regular)
 
 // Handles the processing of a `(condition)` up through the expression.
 //
@@ -524,7 +523,7 @@ CARBON_PARSE_STATE_VARIANTS2(ParenExpressionFinish, Normal, Tuple)
 //   2. PatternFinishAs(Generic|Regular)
 // Else:
 //   1. PatternFinish
-CARBON_PARSE_STATE_VARIANTS4(Pattern, DeducedParameter, Parameter, Variable, Let)
+CARBON_PARSE_STATE_VARIANTS4(Pattern, ImplicitParameter, Parameter, Variable, Let)
 
 // Handles `addr` in a pattern.
 //
diff --git a/toolchain/parse/testdata/class/fn_definitions.carbon b/toolchain/parse/testdata/class/fn_definitions.carbon
index 8ed390623b8a..fb2a7bcb29b7 100644
--- a/toolchain/parse/testdata/class/fn_definitions.carbon
+++ b/toolchain/parse/testdata/class/fn_definitions.carbon
@@ -36,11 +36,11 @@ class Foo {
 // CHECK:STDOUT:       {kind: 'FunctionDefinition', text: '}', subtree_size: 16},
 // CHECK:STDOUT:           {kind: 'FunctionIntroducer', text: 'fn'},
 // CHECK:STDOUT:           {kind: 'Name', text: 'Baz'},
-// CHECK:STDOUT:             {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:             {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:               {kind: 'SelfValueName', text: 'self'},
 // CHECK:STDOUT:               {kind: 'SelfTypeNameExpression', text: 'Self'},
 // CHECK:STDOUT:             {kind: 'PatternBinding', text: ':', subtree_size: 3},
-// CHECK:STDOUT:           {kind: 'DeducedParameterList', text: ']', subtree_size: 5},
+// CHECK:STDOUT:           {kind: 'ImplicitParameterList', text: ']', subtree_size: 5},
 // CHECK:STDOUT:             {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:           {kind: 'ParameterList', text: ')', subtree_size: 2},
 // CHECK:STDOUT:             {kind: 'Literal', text: 'i32'},
@@ -54,13 +54,13 @@ class Foo {
 // CHECK:STDOUT:       {kind: 'FunctionDefinition', text: '}', subtree_size: 18},
 // CHECK:STDOUT:           {kind: 'FunctionIntroducer', text: 'fn'},
 // CHECK:STDOUT:           {kind: 'Name', text: 'Modify'},
-// CHECK:STDOUT:             {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:             {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:                 {kind: 'SelfValueName', text: 'self'},
 // CHECK:STDOUT:                   {kind: 'SelfTypeNameExpression', text: 'Self'},
 // CHECK:STDOUT:                 {kind: 'PostfixOperator', text: '*', subtree_size: 2},
 // CHECK:STDOUT:               {kind: 'PatternBinding', text: ':', subtree_size: 4},
 // CHECK:STDOUT:             {kind: 'Address', text: 'addr', subtree_size: 5},
-// CHECK:STDOUT:           {kind: 'DeducedParameterList', text: ']', subtree_size: 7},
+// CHECK:STDOUT:           {kind: 'ImplicitParameterList', text: ']', subtree_size: 7},
 // CHECK:STDOUT:             {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:           {kind: 'ParameterList', text: ')', subtree_size: 2},
 // CHECK:STDOUT:         {kind: 'FunctionDefinitionStart', text: '{', subtree_size: 12},
diff --git a/toolchain/parse/testdata/function/declaration/fail_missing_deduced_close.carbon b/toolchain/parse/testdata/function/declaration/fail_missing_implicit_close.carbon
similarity index 63%
rename from toolchain/parse/testdata/function/declaration/fail_missing_deduced_close.carbon
rename to toolchain/parse/testdata/function/declaration/fail_missing_implicit_close.carbon
index 1f323b1882f2..8e744b36a7d0 100644
--- a/toolchain/parse/testdata/function/declaration/fail_missing_deduced_close.carbon
+++ b/toolchain/parse/testdata/function/declaration/fail_missing_implicit_close.carbon
@@ -5,27 +5,27 @@
 // AUTOUPDATE
 
 // Fix and uncomment this to test error handling.
-// CHECK:STDERR: fail_missing_deduced_close.carbon:[[@LINE+6]]:7: ERROR: Closing symbol does not match most recent opening symbol.
+// CHECK:STDERR: fail_missing_implicit_close.carbon:[[@LINE+6]]:7: ERROR: Closing symbol does not match most recent opening symbol.
 // CHECK:STDERR: fn Div[();
 // CHECK:STDERR:       ^
-// CHECK:STDERR: fail_missing_deduced_close.carbon:[[@LINE+3]]:8: ERROR: Expected parameter declaration.
+// CHECK:STDERR: fail_missing_implicit_close.carbon:[[@LINE+3]]:8: ERROR: Expected parameter declaration.
 // CHECK:STDERR: fn Div[();
 // CHECK:STDERR:        ^
 fn Div[();
 
-// CHECK:STDERR: fail_missing_deduced_close.carbon:[[@LINE+15]]:21: ERROR: A `(` for parameters is required after deduced parameters.
+// CHECK:STDERR: fail_missing_implicit_close.carbon:[[@LINE+15]]:21: ERROR: A `(` for parameters is required after implicit parameters.
 // CHECK:STDERR: // CHECK:STDOUT:   ]
 // CHECK:STDERR:                     ^
-// CHECK:STDOUT: - filename: fail_missing_deduced_close.carbon
+// CHECK:STDOUT: - filename: fail_missing_implicit_close.carbon
 // CHECK:STDOUT:   parse_tree: [
 // CHECK:STDOUT:     {kind: 'FileStart', text: ''},
 // CHECK:STDOUT:       {kind: 'FunctionIntroducer', text: 'fn'},
 // CHECK:STDOUT:       {kind: 'Name', text: 'Div'},
-// CHECK:STDOUT:         {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:           {kind: 'Name', text: '(', has_error: yes},
 // CHECK:STDOUT:           {kind: 'InvalidParse', text: '(', has_error: yes},
 // CHECK:STDOUT:         {kind: 'PatternBinding', text: '(', has_error: yes, subtree_size: 3},
-// CHECK:STDOUT:       {kind: 'DeducedParameterList', text: ']', has_error: yes, subtree_size: 5},
+// CHECK:STDOUT:       {kind: 'ImplicitParameterList', text: ']', has_error: yes, subtree_size: 5},
 // CHECK:STDOUT:     {kind: 'FunctionDeclaration', text: 'fn', has_error: yes, subtree_size: 8},
 // CHECK:STDOUT:     {kind: 'FileEnd', text: ''},
 // CHECK:STDOUT:   ]
diff --git a/toolchain/parse/testdata/function/declaration/deduced_empty.carbon b/toolchain/parse/testdata/function/declaration/implicit_empty.carbon
similarity index 77%
rename from toolchain/parse/testdata/function/declaration/deduced_empty.carbon
rename to toolchain/parse/testdata/function/declaration/implicit_empty.carbon
index 5f90f62bdac0..3137916210b2 100644
--- a/toolchain/parse/testdata/function/declaration/deduced_empty.carbon
+++ b/toolchain/parse/testdata/function/declaration/implicit_empty.carbon
@@ -6,13 +6,13 @@
 
 fn foo[]();
 
-// CHECK:STDOUT: - filename: deduced_empty.carbon
+// CHECK:STDOUT: - filename: implicit_empty.carbon
 // CHECK:STDOUT:   parse_tree: [
 // CHECK:STDOUT:     {kind: 'FileStart', text: ''},
 // CHECK:STDOUT:       {kind: 'FunctionIntroducer', text: 'fn'},
 // CHECK:STDOUT:       {kind: 'Name', text: 'foo'},
-// CHECK:STDOUT:         {kind: 'DeducedParameterListStart', text: '['},
-// CHECK:STDOUT:       {kind: 'DeducedParameterList', text: ']', subtree_size: 2},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterListStart', text: '['},
+// CHECK:STDOUT:       {kind: 'ImplicitParameterList', text: ']', subtree_size: 2},
 // CHECK:STDOUT:         {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:       {kind: 'ParameterList', text: ')', subtree_size: 2},
 // CHECK:STDOUT:     {kind: 'FunctionDeclaration', text: ';', subtree_size: 7},
diff --git a/toolchain/parse/testdata/function/declaration/deduced_params.carbon b/toolchain/parse/testdata/function/declaration/implicit_params.carbon
similarity index 84%
rename from toolchain/parse/testdata/function/declaration/deduced_params.carbon
rename to toolchain/parse/testdata/function/declaration/implicit_params.carbon
index 5d34f584761a..b81d8af0dc7d 100644
--- a/toolchain/parse/testdata/function/declaration/deduced_params.carbon
+++ b/toolchain/parse/testdata/function/declaration/implicit_params.carbon
@@ -6,12 +6,12 @@
 
 fn foo[a: i32, b: i32]();
 
-// CHECK:STDOUT: - filename: deduced_params.carbon
+// CHECK:STDOUT: - filename: implicit_params.carbon
 // CHECK:STDOUT:   parse_tree: [
 // CHECK:STDOUT:     {kind: 'FileStart', text: ''},
 // CHECK:STDOUT:       {kind: 'FunctionIntroducer', text: 'fn'},
 // CHECK:STDOUT:       {kind: 'Name', text: 'foo'},
-// CHECK:STDOUT:         {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:           {kind: 'Name', text: 'a'},
 // CHECK:STDOUT:           {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:         {kind: 'PatternBinding', text: ':', subtree_size: 3},
@@ -19,7 +19,7 @@ fn foo[a: i32, b: i32]();
 // CHECK:STDOUT:           {kind: 'Name', text: 'b'},
 // CHECK:STDOUT:           {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:         {kind: 'PatternBinding', text: ':', subtree_size: 3},
-// CHECK:STDOUT:       {kind: 'DeducedParameterList', text: ']', subtree_size: 9},
+// CHECK:STDOUT:       {kind: 'ImplicitParameterList', text: ']', subtree_size: 9},
 // CHECK:STDOUT:         {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:       {kind: 'ParameterList', text: ')', subtree_size: 2},
 // CHECK:STDOUT:     {kind: 'FunctionDeclaration', text: ';', subtree_size: 14},
diff --git a/toolchain/parse/testdata/generics/deduced_params/empty.carbon b/toolchain/parse/testdata/generics/deduced_params/empty.carbon
index 022387078386..3eee06a8a06a 100644
--- a/toolchain/parse/testdata/generics/deduced_params/empty.carbon
+++ b/toolchain/parse/testdata/generics/deduced_params/empty.carbon
@@ -13,15 +13,15 @@ interface Bar[]() {}
 // CHECK:STDOUT:     {kind: 'FileStart', text: ''},
 // CHECK:STDOUT:       {kind: 'ClassIntroducer', text: 'class'},
 // CHECK:STDOUT:       {kind: 'Name', text: 'Foo'},
-// CHECK:STDOUT:         {kind: 'DeducedParameterListStart', text: '['},
-// CHECK:STDOUT:       {kind: 'DeducedParameterList', text: ']', subtree_size: 2},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterListStart', text: '['},
+// CHECK:STDOUT:       {kind: 'ImplicitParameterList', text: ']', subtree_size: 2},
 // CHECK:STDOUT:         {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:       {kind: 'ParameterList', text: ')', subtree_size: 2},
 // CHECK:STDOUT:     {kind: 'ClassDeclaration', text: ';', subtree_size: 7},
 // CHECK:STDOUT:         {kind: 'InterfaceIntroducer', text: 'interface'},
 // CHECK:STDOUT:         {kind: 'Name', text: 'Bar'},
-// CHECK:STDOUT:           {kind: 'DeducedParameterListStart', text: '['},
-// CHECK:STDOUT:         {kind: 'DeducedParameterList', text: ']', subtree_size: 2},
+// CHECK:STDOUT:           {kind: 'ImplicitParameterListStart', text: '['},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterList', text: ']', subtree_size: 2},
 // CHECK:STDOUT:           {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:         {kind: 'ParameterList', text: ')', subtree_size: 2},
 // CHECK:STDOUT:       {kind: 'InterfaceDefinitionStart', text: '{', subtree_size: 7},
diff --git a/toolchain/parse/testdata/generics/deduced_params/fail_no_parens.carbon b/toolchain/parse/testdata/generics/deduced_params/fail_no_parens.carbon
index 62598f580722..e2650c2a1c2c 100644
--- a/toolchain/parse/testdata/generics/deduced_params/fail_no_parens.carbon
+++ b/toolchain/parse/testdata/generics/deduced_params/fail_no_parens.carbon
@@ -4,22 +4,22 @@
 //
 // AUTOUPDATE
 
-// CHECK:STDERR: fail_no_parens.carbon:[[@LINE+3]]:12: ERROR: A `(` for parameters is required after deduced parameters.
+// CHECK:STDERR: fail_no_parens.carbon:[[@LINE+3]]:12: ERROR: A `(` for parameters is required after implicit parameters.
 // CHECK:STDERR: class Foo[];
 // CHECK:STDERR:            ^
 class Foo[];
 
-// CHECK:STDERR: fail_no_parens.carbon:[[@LINE+3]]:18: ERROR: A `(` for parameters is required after deduced parameters.
+// CHECK:STDERR: fail_no_parens.carbon:[[@LINE+3]]:18: ERROR: A `(` for parameters is required after implicit parameters.
 // CHECK:STDERR: class Foo[a: i32];
 // CHECK:STDERR:                  ^
 class Foo[a: i32];
 
-// CHECK:STDERR: fail_no_parens.carbon:[[@LINE+3]]:17: ERROR: A `(` for parameters is required after deduced parameters.
+// CHECK:STDERR: fail_no_parens.carbon:[[@LINE+3]]:17: ERROR: A `(` for parameters is required after implicit parameters.
 // CHECK:STDERR: interface Bar[] {}
 // CHECK:STDERR:                 ^
 interface Bar[] {}
 
-// CHECK:STDERR: fail_no_parens.carbon:[[@LINE+3]]:23: ERROR: A `(` for parameters is required after deduced parameters.
+// CHECK:STDERR: fail_no_parens.carbon:[[@LINE+3]]:23: ERROR: A `(` for parameters is required after implicit parameters.
 // CHECK:STDERR: interface Bar[a: i32] {}
 // CHECK:STDERR:                       ^
 interface Bar[a: i32] {}
@@ -29,29 +29,29 @@ interface Bar[a: i32] {}
 // CHECK:STDOUT:     {kind: 'FileStart', text: ''},
 // CHECK:STDOUT:       {kind: 'ClassIntroducer', text: 'class'},
 // CHECK:STDOUT:       {kind: 'Name', text: 'Foo'},
-// CHECK:STDOUT:         {kind: 'DeducedParameterListStart', text: '['},
-// CHECK:STDOUT:       {kind: 'DeducedParameterList', text: ']', subtree_size: 2},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterListStart', text: '['},
+// CHECK:STDOUT:       {kind: 'ImplicitParameterList', text: ']', subtree_size: 2},
 // CHECK:STDOUT:     {kind: 'ClassDeclaration', text: ';', has_error: yes, subtree_size: 5},
 // CHECK:STDOUT:       {kind: 'ClassIntroducer', text: 'class'},
 // CHECK:STDOUT:       {kind: 'Name', text: 'Foo'},
-// CHECK:STDOUT:         {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:           {kind: 'Name', text: 'a'},
 // CHECK:STDOUT:           {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:         {kind: 'PatternBinding', text: ':', subtree_size: 3},
-// CHECK:STDOUT:       {kind: 'DeducedParameterList', text: ']', subtree_size: 5},
+// CHECK:STDOUT:       {kind: 'ImplicitParameterList', text: ']', subtree_size: 5},
 // CHECK:STDOUT:     {kind: 'ClassDeclaration', text: ';', has_error: yes, subtree_size: 8},
 // CHECK:STDOUT:       {kind: 'InterfaceIntroducer', text: 'interface'},
 // CHECK:STDOUT:       {kind: 'Name', text: 'Bar'},
-// CHECK:STDOUT:         {kind: 'DeducedParameterListStart', text: '['},
-// CHECK:STDOUT:       {kind: 'DeducedParameterList', text: ']', subtree_size: 2},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterListStart', text: '['},
+// CHECK:STDOUT:       {kind: 'ImplicitParameterList', text: ']', subtree_size: 2},
 // CHECK:STDOUT:     {kind: 'InterfaceDeclaration', text: 'interface', has_error: yes, subtree_size: 5},
 // CHECK:STDOUT:       {kind: 'InterfaceIntroducer', text: 'interface'},
 // CHECK:STDOUT:       {kind: 'Name', text: 'Bar'},
-// CHECK:STDOUT:         {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:           {kind: 'Name', text: 'a'},
 // CHECK:STDOUT:           {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:         {kind: 'PatternBinding', text: ':', subtree_size: 3},
-// CHECK:STDOUT:       {kind: 'DeducedParameterList', text: ']', subtree_size: 5},
+// CHECK:STDOUT:       {kind: 'ImplicitParameterList', text: ']', subtree_size: 5},
 // CHECK:STDOUT:     {kind: 'InterfaceDeclaration', text: 'interface', has_error: yes, subtree_size: 8},
 // CHECK:STDOUT:     {kind: 'FileEnd', text: ''},
 // CHECK:STDOUT:   ]
diff --git a/toolchain/parse/testdata/generics/deduced_params/one.carbon b/toolchain/parse/testdata/generics/deduced_params/one.carbon
index fb57825f2eb4..fa80864bb39d 100644
--- a/toolchain/parse/testdata/generics/deduced_params/one.carbon
+++ b/toolchain/parse/testdata/generics/deduced_params/one.carbon
@@ -13,21 +13,21 @@ interface Bar[a: i32]() {}
 // CHECK:STDOUT:     {kind: 'FileStart', text: ''},
 // CHECK:STDOUT:       {kind: 'ClassIntroducer', text: 'class'},
 // CHECK:STDOUT:       {kind: 'Name', text: 'Foo'},
-// CHECK:STDOUT:         {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:           {kind: 'Name', text: 'a'},
 // CHECK:STDOUT:           {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:         {kind: 'PatternBinding', text: ':', subtree_size: 3},
-// CHECK:STDOUT:       {kind: 'DeducedParameterList', text: ']', subtree_size: 5},
+// CHECK:STDOUT:       {kind: 'ImplicitParameterList', text: ']', subtree_size: 5},
 // CHECK:STDOUT:         {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:       {kind: 'ParameterList', text: ')', subtree_size: 2},
 // CHECK:STDOUT:     {kind: 'ClassDeclaration', text: ';', subtree_size: 10},
 // CHECK:STDOUT:         {kind: 'InterfaceIntroducer', text: 'interface'},
 // CHECK:STDOUT:         {kind: 'Name', text: 'Bar'},
-// CHECK:STDOUT:           {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:           {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:             {kind: 'Name', text: 'a'},
 // CHECK:STDOUT:             {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:           {kind: 'PatternBinding', text: ':', subtree_size: 3},
-// CHECK:STDOUT:         {kind: 'DeducedParameterList', text: ']', subtree_size: 5},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterList', text: ']', subtree_size: 5},
 // CHECK:STDOUT:           {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:         {kind: 'ParameterList', text: ')', subtree_size: 2},
 // CHECK:STDOUT:       {kind: 'InterfaceDefinitionStart', text: '{', subtree_size: 10},
diff --git a/toolchain/parse/testdata/generics/deduced_params/one_suffix_comma.carbon b/toolchain/parse/testdata/generics/deduced_params/one_suffix_comma.carbon
index d18eb7750c06..3caaed13a080 100644
--- a/toolchain/parse/testdata/generics/deduced_params/one_suffix_comma.carbon
+++ b/toolchain/parse/testdata/generics/deduced_params/one_suffix_comma.carbon
@@ -13,23 +13,23 @@ interface Bar[a: i32,]() {}
 // CHECK:STDOUT:     {kind: 'FileStart', text: ''},
 // CHECK:STDOUT:       {kind: 'ClassIntroducer', text: 'class'},
 // CHECK:STDOUT:       {kind: 'Name', text: 'Foo'},
-// CHECK:STDOUT:         {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:           {kind: 'Name', text: 'a'},
 // CHECK:STDOUT:           {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:         {kind: 'PatternBinding', text: ':', subtree_size: 3},
 // CHECK:STDOUT:         {kind: 'ParameterListComma', text: ','},
-// CHECK:STDOUT:       {kind: 'DeducedParameterList', text: ']', subtree_size: 6},
+// CHECK:STDOUT:       {kind: 'ImplicitParameterList', text: ']', subtree_size: 6},
 // CHECK:STDOUT:         {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:       {kind: 'ParameterList', text: ')', subtree_size: 2},
 // CHECK:STDOUT:     {kind: 'ClassDeclaration', text: ';', subtree_size: 11},
 // CHECK:STDOUT:         {kind: 'InterfaceIntroducer', text: 'interface'},
 // CHECK:STDOUT:         {kind: 'Name', text: 'Bar'},
-// CHECK:STDOUT:           {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:           {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:             {kind: 'Name', text: 'a'},
 // CHECK:STDOUT:             {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:           {kind: 'PatternBinding', text: ':', subtree_size: 3},
 // CHECK:STDOUT:           {kind: 'ParameterListComma', text: ','},
-// CHECK:STDOUT:         {kind: 'DeducedParameterList', text: ']', subtree_size: 6},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterList', text: ']', subtree_size: 6},
 // CHECK:STDOUT:           {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:         {kind: 'ParameterList', text: ')', subtree_size: 2},
 // CHECK:STDOUT:       {kind: 'InterfaceDefinitionStart', text: '{', subtree_size: 11},
diff --git a/toolchain/parse/testdata/generics/deduced_params/six.carbon b/toolchain/parse/testdata/generics/deduced_params/six.carbon
index 0481f1f04226..f5223dd24e90 100644
--- a/toolchain/parse/testdata/generics/deduced_params/six.carbon
+++ b/toolchain/parse/testdata/generics/deduced_params/six.carbon
@@ -13,7 +13,7 @@ interface Bar[a: i32, b: i32, c: i32, d: i32, e: i32, f: i32]() {}
 // CHECK:STDOUT:     {kind: 'FileStart', text: ''},
 // CHECK:STDOUT:       {kind: 'ClassIntroducer', text: 'class'},
 // CHECK:STDOUT:       {kind: 'Name', text: 'Foo'},
-// CHECK:STDOUT:         {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:           {kind: 'Name', text: 'a'},
 // CHECK:STDOUT:           {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:         {kind: 'PatternBinding', text: ':', subtree_size: 3},
@@ -37,13 +37,13 @@ interface Bar[a: i32, b: i32, c: i32, d: i32, e: i32, f: i32]() {}
 // CHECK:STDOUT:           {kind: 'Name', text: 'f'},
 // CHECK:STDOUT:           {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:         {kind: 'PatternBinding', text: ':', subtree_size: 3},
-// CHECK:STDOUT:       {kind: 'DeducedParameterList', text: ']', subtree_size: 25},
+// CHECK:STDOUT:       {kind: 'ImplicitParameterList', text: ']', subtree_size: 25},
 // CHECK:STDOUT:         {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:       {kind: 'ParameterList', text: ')', subtree_size: 2},
 // CHECK:STDOUT:     {kind: 'ClassDeclaration', text: ';', subtree_size: 30},
 // CHECK:STDOUT:         {kind: 'InterfaceIntroducer', text: 'interface'},
 // CHECK:STDOUT:         {kind: 'Name', text: 'Bar'},
-// CHECK:STDOUT:           {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:           {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:             {kind: 'Name', text: 'a'},
 // CHECK:STDOUT:             {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:           {kind: 'PatternBinding', text: ':', subtree_size: 3},
@@ -67,7 +67,7 @@ interface Bar[a: i32, b: i32, c: i32, d: i32, e: i32, f: i32]() {}
 // CHECK:STDOUT:             {kind: 'Name', text: 'f'},
 // CHECK:STDOUT:             {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:           {kind: 'PatternBinding', text: ':', subtree_size: 3},
-// CHECK:STDOUT:         {kind: 'DeducedParameterList', text: ']', subtree_size: 25},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterList', text: ']', subtree_size: 25},
 // CHECK:STDOUT:           {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:         {kind: 'ParameterList', text: ')', subtree_size: 2},
 // CHECK:STDOUT:       {kind: 'InterfaceDefinitionStart', text: '{', subtree_size: 30},
diff --git a/toolchain/parse/testdata/generics/deduced_params/two.carbon b/toolchain/parse/testdata/generics/deduced_params/two.carbon
index f94ab44b458d..1adc915db9a2 100644
--- a/toolchain/parse/testdata/generics/deduced_params/two.carbon
+++ b/toolchain/parse/testdata/generics/deduced_params/two.carbon
@@ -13,7 +13,7 @@ interface Bar[a: i32, b: i32]() {}
 // CHECK:STDOUT:     {kind: 'FileStart', text: ''},
 // CHECK:STDOUT:       {kind: 'ClassIntroducer', text: 'class'},
 // CHECK:STDOUT:       {kind: 'Name', text: 'Foo'},
-// CHECK:STDOUT:         {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:           {kind: 'Name', text: 'a'},
 // CHECK:STDOUT:           {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:         {kind: 'PatternBinding', text: ':', subtree_size: 3},
@@ -21,13 +21,13 @@ interface Bar[a: i32, b: i32]() {}
 // CHECK:STDOUT:           {kind: 'Name', text: 'b'},
 // CHECK:STDOUT:           {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:         {kind: 'PatternBinding', text: ':', subtree_size: 3},
-// CHECK:STDOUT:       {kind: 'DeducedParameterList', text: ']', subtree_size: 9},
+// CHECK:STDOUT:       {kind: 'ImplicitParameterList', text: ']', subtree_size: 9},
 // CHECK:STDOUT:         {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:       {kind: 'ParameterList', text: ')', subtree_size: 2},
 // CHECK:STDOUT:     {kind: 'ClassDeclaration', text: ';', subtree_size: 14},
 // CHECK:STDOUT:         {kind: 'InterfaceIntroducer', text: 'interface'},
 // CHECK:STDOUT:         {kind: 'Name', text: 'Bar'},
-// CHECK:STDOUT:           {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:           {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:             {kind: 'Name', text: 'a'},
 // CHECK:STDOUT:             {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:           {kind: 'PatternBinding', text: ':', subtree_size: 3},
@@ -35,7 +35,7 @@ interface Bar[a: i32, b: i32]() {}
 // CHECK:STDOUT:             {kind: 'Name', text: 'b'},
 // CHECK:STDOUT:             {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:           {kind: 'PatternBinding', text: ':', subtree_size: 3},
-// CHECK:STDOUT:         {kind: 'DeducedParameterList', text: ']', subtree_size: 9},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterList', text: ']', subtree_size: 9},
 // CHECK:STDOUT:           {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:         {kind: 'ParameterList', text: ')', subtree_size: 2},
 // CHECK:STDOUT:       {kind: 'InterfaceDefinitionStart', text: '{', subtree_size: 14},
diff --git a/toolchain/parse/testdata/generics/deduced_params/two_suffix_comma.carbon b/toolchain/parse/testdata/generics/deduced_params/two_suffix_comma.carbon
index 5cf863d7f937..b188951ca098 100644
--- a/toolchain/parse/testdata/generics/deduced_params/two_suffix_comma.carbon
+++ b/toolchain/parse/testdata/generics/deduced_params/two_suffix_comma.carbon
@@ -13,7 +13,7 @@ interface Bar[a: i32, b: i32,]() {}
 // CHECK:STDOUT:     {kind: 'FileStart', text: ''},
 // CHECK:STDOUT:       {kind: 'ClassIntroducer', text: 'class'},
 // CHECK:STDOUT:       {kind: 'Name', text: 'Foo'},
-// CHECK:STDOUT:         {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:           {kind: 'Name', text: 'a'},
 // CHECK:STDOUT:           {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:         {kind: 'PatternBinding', text: ':', subtree_size: 3},
@@ -22,13 +22,13 @@ interface Bar[a: i32, b: i32,]() {}
 // CHECK:STDOUT:           {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:         {kind: 'PatternBinding', text: ':', subtree_size: 3},
 // CHECK:STDOUT:         {kind: 'ParameterListComma', text: ','},
-// CHECK:STDOUT:       {kind: 'DeducedParameterList', text: ']', subtree_size: 10},
+// CHECK:STDOUT:       {kind: 'ImplicitParameterList', text: ']', subtree_size: 10},
 // CHECK:STDOUT:         {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:       {kind: 'ParameterList', text: ')', subtree_size: 2},
 // CHECK:STDOUT:     {kind: 'ClassDeclaration', text: ';', subtree_size: 15},
 // CHECK:STDOUT:         {kind: 'InterfaceIntroducer', text: 'interface'},
 // CHECK:STDOUT:         {kind: 'Name', text: 'Bar'},
-// CHECK:STDOUT:           {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:           {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:             {kind: 'Name', text: 'a'},
 // CHECK:STDOUT:             {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:           {kind: 'PatternBinding', text: ':', subtree_size: 3},
@@ -37,7 +37,7 @@ interface Bar[a: i32, b: i32,]() {}
 // CHECK:STDOUT:             {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:           {kind: 'PatternBinding', text: ':', subtree_size: 3},
 // CHECK:STDOUT:           {kind: 'ParameterListComma', text: ','},
-// CHECK:STDOUT:         {kind: 'DeducedParameterList', text: ']', subtree_size: 10},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterList', text: ']', subtree_size: 10},
 // CHECK:STDOUT:           {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:         {kind: 'ParameterList', text: ')', subtree_size: 2},
 // CHECK:STDOUT:       {kind: 'InterfaceDefinitionStart', text: '{', subtree_size: 15},
diff --git a/toolchain/parse/testdata/generics/interface/basic.carbon b/toolchain/parse/testdata/generics/interface/basic.carbon
index b467df71a7cb..4829e2517b69 100644
--- a/toolchain/parse/testdata/generics/interface/basic.carbon
+++ b/toolchain/parse/testdata/generics/interface/basic.carbon
@@ -17,11 +17,11 @@ interface Foo {
 // CHECK:STDOUT:       {kind: 'InterfaceDefinitionStart', text: '{', subtree_size: 3},
 // CHECK:STDOUT:         {kind: 'FunctionIntroducer', text: 'fn'},
 // CHECK:STDOUT:         {kind: 'Name', text: 'Add'},
-// CHECK:STDOUT:           {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:           {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:             {kind: 'SelfValueName', text: 'self'},
 // CHECK:STDOUT:             {kind: 'SelfTypeNameExpression', text: 'Self'},
 // CHECK:STDOUT:           {kind: 'PatternBinding', text: ':', subtree_size: 3},
-// CHECK:STDOUT:         {kind: 'DeducedParameterList', text: ']', subtree_size: 5},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterList', text: ']', subtree_size: 5},
 // CHECK:STDOUT:           {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:             {kind: 'Name', text: 'b'},
 // CHECK:STDOUT:             {kind: 'SelfTypeNameExpression', text: 'Self'},
@@ -32,11 +32,11 @@ interface Foo {
 // CHECK:STDOUT:       {kind: 'FunctionDeclaration', text: ';', subtree_size: 15},
 // CHECK:STDOUT:         {kind: 'FunctionIntroducer', text: 'fn'},
 // CHECK:STDOUT:         {kind: 'Name', text: 'Add'},
-// CHECK:STDOUT:           {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:           {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:             {kind: 'SelfValueName', text: 'self'},
 // CHECK:STDOUT:             {kind: 'NameExpression', text: 'foo'},
 // CHECK:STDOUT:           {kind: 'PatternBinding', text: ':', subtree_size: 3},
-// CHECK:STDOUT:         {kind: 'DeducedParameterList', text: ']', subtree_size: 5},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterList', text: ']', subtree_size: 5},
 // CHECK:STDOUT:           {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:             {kind: 'Name', text: 'b'},
 // CHECK:STDOUT:             {kind: 'SelfTypeNameExpression', text: 'Self'},
diff --git a/toolchain/parse/testdata/generics/interface/fail_no_impl_allowed.carbon b/toolchain/parse/testdata/generics/interface/fail_no_impl_allowed.carbon
index b75a5d2f40ce..44ce2416c193 100644
--- a/toolchain/parse/testdata/generics/interface/fail_no_impl_allowed.carbon
+++ b/toolchain/parse/testdata/generics/interface/fail_no_impl_allowed.carbon
@@ -21,11 +21,11 @@ interface Foo {
 // CHECK:STDOUT:       {kind: 'InterfaceDefinitionStart', text: '{', subtree_size: 3},
 // CHECK:STDOUT:         {kind: 'FunctionIntroducer', text: 'fn'},
 // CHECK:STDOUT:         {kind: 'Name', text: 'Add'},
-// CHECK:STDOUT:           {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:           {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:             {kind: 'SelfValueName', text: 'self'},
 // CHECK:STDOUT:             {kind: 'SelfTypeNameExpression', text: 'Self'},
 // CHECK:STDOUT:           {kind: 'PatternBinding', text: ':', subtree_size: 3},
-// CHECK:STDOUT:         {kind: 'DeducedParameterList', text: ']', subtree_size: 5},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterList', text: ']', subtree_size: 5},
 // CHECK:STDOUT:           {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:             {kind: 'Name', text: 'b'},
 // CHECK:STDOUT:             {kind: 'SelfTypeNameExpression', text: 'Self'},
diff --git a/toolchain/parse/testdata/generics/interface/fail_self_param_syntax.carbon b/toolchain/parse/testdata/generics/interface/fail_self_param_syntax.carbon
index 1dcf49d1b12d..2172874a1fb9 100644
--- a/toolchain/parse/testdata/generics/interface/fail_self_param_syntax.carbon
+++ b/toolchain/parse/testdata/generics/interface/fail_self_param_syntax.carbon
@@ -24,11 +24,11 @@ interface Foo {
 // CHECK:STDOUT:       {kind: 'InterfaceDefinitionStart', text: '{', subtree_size: 3},
 // CHECK:STDOUT:         {kind: 'FunctionIntroducer', text: 'fn'},
 // CHECK:STDOUT:         {kind: 'Name', text: 'Sub'},
-// CHECK:STDOUT:           {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:           {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:             {kind: 'Name', text: 'me'},
 // CHECK:STDOUT:             {kind: 'InvalidParse', text: 'Self', has_error: yes},
 // CHECK:STDOUT:           {kind: 'PatternBinding', text: 'me', has_error: yes, subtree_size: 3},
-// CHECK:STDOUT:         {kind: 'DeducedParameterList', text: ']', has_error: yes, subtree_size: 5},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterList', text: ']', has_error: yes, subtree_size: 5},
 // CHECK:STDOUT:           {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:             {kind: 'Name', text: 'b'},
 // CHECK:STDOUT:             {kind: 'SelfTypeNameExpression', text: 'Self'},
@@ -39,11 +39,11 @@ interface Foo {
 // CHECK:STDOUT:       {kind: 'FunctionDeclaration', text: ';', subtree_size: 15},
 // CHECK:STDOUT:         {kind: 'FunctionIntroducer', text: 'fn'},
 // CHECK:STDOUT:         {kind: 'Name', text: 'Mul'},
-// CHECK:STDOUT:           {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:           {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:             {kind: 'Name', text: 'Self', has_error: yes},
 // CHECK:STDOUT:             {kind: 'InvalidParse', text: 'Self', has_error: yes},
 // CHECK:STDOUT:           {kind: 'PatternBinding', text: 'Self', has_error: yes, subtree_size: 3},
-// CHECK:STDOUT:         {kind: 'DeducedParameterList', text: ']', has_error: yes, subtree_size: 5},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterList', text: ']', has_error: yes, subtree_size: 5},
 // CHECK:STDOUT:           {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:             {kind: 'Name', text: 'b'},
 // CHECK:STDOUT:             {kind: 'SelfTypeNameExpression', text: 'Self'},
diff --git a/toolchain/parse/testdata/generics/interface/self_pointer.carbon b/toolchain/parse/testdata/generics/interface/self_pointer.carbon
index df3e0409d1d0..d0af70810f42 100644
--- a/toolchain/parse/testdata/generics/interface/self_pointer.carbon
+++ b/toolchain/parse/testdata/generics/interface/self_pointer.carbon
@@ -17,13 +17,13 @@ interface Foo {
 // CHECK:STDOUT:       {kind: 'InterfaceDefinitionStart', text: '{', subtree_size: 3},
 // CHECK:STDOUT:         {kind: 'FunctionIntroducer', text: 'fn'},
 // CHECK:STDOUT:         {kind: 'Name', text: 'Sub'},
-// CHECK:STDOUT:           {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:           {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:               {kind: 'SelfValueName', text: 'self'},
 // CHECK:STDOUT:                 {kind: 'SelfTypeNameExpression', text: 'Self'},
 // CHECK:STDOUT:               {kind: 'PostfixOperator', text: '*', subtree_size: 2},
 // CHECK:STDOUT:             {kind: 'PatternBinding', text: ':', subtree_size: 4},
 // CHECK:STDOUT:           {kind: 'Address', text: 'addr', subtree_size: 5},
-// CHECK:STDOUT:         {kind: 'DeducedParameterList', text: ']', subtree_size: 7},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterList', text: ']', subtree_size: 7},
 // CHECK:STDOUT:           {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:             {kind: 'Name', text: 'b'},
 // CHECK:STDOUT:             {kind: 'SelfTypeNameExpression', text: 'Self'},
@@ -34,13 +34,13 @@ interface Foo {
 // CHECK:STDOUT:       {kind: 'FunctionDeclaration', text: ';', subtree_size: 17},
 // CHECK:STDOUT:         {kind: 'FunctionIntroducer', text: 'fn'},
 // CHECK:STDOUT:         {kind: 'Name', text: 'Sub'},
-// CHECK:STDOUT:           {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:           {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:               {kind: 'SelfValueName', text: 'self'},
 // CHECK:STDOUT:                 {kind: 'NameExpression', text: 'foo'},
 // CHECK:STDOUT:               {kind: 'PostfixOperator', text: '*', subtree_size: 2},
 // CHECK:STDOUT:             {kind: 'PatternBinding', text: ':', subtree_size: 4},
 // CHECK:STDOUT:           {kind: 'Address', text: 'addr', subtree_size: 5},
-// CHECK:STDOUT:         {kind: 'DeducedParameterList', text: ']', subtree_size: 7},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterList', text: ']', subtree_size: 7},
 // CHECK:STDOUT:           {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:             {kind: 'Name', text: 'b'},
 // CHECK:STDOUT:             {kind: 'SelfTypeNameExpression', text: 'Self'},
diff --git a/toolchain/parse/testdata/generics/named_constraint/fail_no_impl_allowed.carbon b/toolchain/parse/testdata/generics/named_constraint/fail_no_impl_allowed.carbon
index a4c0835a066a..34e518014a3d 100644
--- a/toolchain/parse/testdata/generics/named_constraint/fail_no_impl_allowed.carbon
+++ b/toolchain/parse/testdata/generics/named_constraint/fail_no_impl_allowed.carbon
@@ -19,11 +19,11 @@ constraint Foo {
 // CHECK:STDOUT:       {kind: 'NamedConstraintDefinitionStart', text: '{', subtree_size: 3},
 // CHECK:STDOUT:         {kind: 'FunctionIntroducer', text: 'fn'},
 // CHECK:STDOUT:         {kind: 'Name', text: 'Add'},
-// CHECK:STDOUT:           {kind: 'DeducedParameterListStart', text: '['},
+// CHECK:STDOUT:           {kind: 'ImplicitParameterListStart', text: '['},
 // CHECK:STDOUT:             {kind: 'SelfValueName', text: 'self'},
 // CHECK:STDOUT:             {kind: 'SelfTypeNameExpression', text: 'Self'},
 // CHECK:STDOUT:           {kind: 'PatternBinding', text: ':', subtree_size: 3},
-// CHECK:STDOUT:         {kind: 'DeducedParameterList', text: ']', subtree_size: 5},
+// CHECK:STDOUT:         {kind: 'ImplicitParameterList', text: ']', subtree_size: 5},
 // CHECK:STDOUT:           {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:             {kind: 'Name', text: 'b'},
 // CHECK:STDOUT:             {kind: 'SelfTypeNameExpression', text: 'Self'},