diff --git a/mypy/checker.py b/mypy/checker.py
index d371f40ccaae..060be2c39b1f 100644
--- a/mypy/checker.py
+++ b/mypy/checker.py
@@ -1792,7 +1792,7 @@ def is_unannotated_any(t: Type) -> bool:
                     if is_unannotated_any(self.get_coroutine_return_type(ret_type)):
                         self.fail(message_registry.RETURN_TYPE_EXPECTED, fdef)
                 if any(is_unannotated_any(t) for t in fdef.type.arg_types):
-                    self.fail(message_registry.ARGUMENT_TYPE_EXPECTED, fdef)
+                    self.fail(message_registry.PARAM_TYPE_EXPECTED, fdef)
 
     def check___new___signature(self, fdef: FuncDef, typ: CallableType) -> None:
         self_type = fill_typevars_with_any(fdef.info)
diff --git a/mypy/fastparse.py b/mypy/fastparse.py
index a8ed5eb038f5..8ef905a567d1 100644
--- a/mypy/fastparse.py
+++ b/mypy/fastparse.py
@@ -1001,21 +1001,21 @@ def do_func_def(
         if any(arg_types) or return_type:
             if len(arg_types) != 1 and any(isinstance(t, EllipsisType) for t in arg_types):
                 self.fail(
-                    message_registry.ELLIPSIS_WITH_OTHER_TYPEARGS,
+                    message_registry.ELLIPSIS_WITH_OTHER_TYPEPARAMS,
                     lineno,
                     n.col_offset,
                     blocker=False,
                 )
             elif len(arg_types) > len(arg_kinds):
                 self.fail(
-                    message_registry.TYPE_SIGNATURE_TOO_MANY_ARGS,
+                    message_registry.TYPE_SIGNATURE_TOO_MANY_PARAMS,
                     lineno,
                     n.col_offset,
                     blocker=False,
                 )
             elif len(arg_types) < len(arg_kinds):
                 self.fail(
-                    message_registry.TYPE_SIGNATURE_TOO_FEW_ARGS,
+                    message_registry.TYPE_SIGNATURE_TOO_FEW_PARAMS,
                     lineno,
                     n.col_offset,
                     blocker=False,
diff --git a/mypy/message_registry.py b/mypy/message_registry.py
index cfeb27b1a5c9..61a0764bd483 100644
--- a/mypy/message_registry.py
+++ b/mypy/message_registry.py
@@ -126,8 +126,8 @@ def with_additional_msg(self, info: str) -> ErrorMessage:
 RETURN_TYPE_EXPECTED: Final = ErrorMessage(
     "Function is missing a return type annotation", codes.NO_UNTYPED_DEF
 )
-ARGUMENT_TYPE_EXPECTED: Final = ErrorMessage(
-    "Function is missing a type annotation for one or more arguments", codes.NO_UNTYPED_DEF
+PARAM_TYPE_EXPECTED: Final = ErrorMessage(
+    "Function is missing a type annotation for one or more parameters", codes.NO_UNTYPED_DEF
 )
 KEYWORD_ARGUMENT_REQUIRES_STR_KEY_TYPE: Final = ErrorMessage(
     'Keyword argument only valid with "str" key type in call to "dict"'
@@ -224,7 +224,7 @@ def with_additional_msg(self, info: str) -> ErrorMessage:
 
 # Self-type
 MISSING_OR_INVALID_SELF_TYPE: Final = ErrorMessage(
-    "Self argument missing for a non-static method (or an invalid type for self)"
+    "self parameter missing for a non-static method (or an invalid type for self)"
 )
 ERASED_SELF_TYPE_NOT_SUPERTYPE: Final = ErrorMessage(
     'The erased type of self "{}" is not a supertype of its class "{}"'
@@ -308,14 +308,14 @@ def with_additional_msg(self, info: str) -> ErrorMessage:
 TYPE_COMMENT_SYNTAX_ERROR_VALUE: Final = ErrorMessage(
     'Syntax error in type comment "{}"', codes.SYNTAX
 )
-ELLIPSIS_WITH_OTHER_TYPEARGS: Final = ErrorMessage(
-    "Ellipses cannot accompany other argument types in function type signature", codes.SYNTAX
+ELLIPSIS_WITH_OTHER_TYPEPARAMS: Final = ErrorMessage(
+    "Ellipses cannot accompany other parameter types in function type signature", codes.SYNTAX
 )
-TYPE_SIGNATURE_TOO_MANY_ARGS: Final = ErrorMessage(
-    "Type signature has too many arguments", codes.SYNTAX
+TYPE_SIGNATURE_TOO_MANY_PARAMS: Final = ErrorMessage(
+    "Type signature has too many parameters", codes.SYNTAX
 )
-TYPE_SIGNATURE_TOO_FEW_ARGS: Final = ErrorMessage(
-    "Type signature has too few arguments", codes.SYNTAX
+TYPE_SIGNATURE_TOO_FEW_PARAMS: Final = ErrorMessage(
+    "Type signature has too few parameters", codes.SYNTAX
 )
 ARG_CONSTRUCTOR_NAME_EXPECTED: Final = ErrorMessage("Expected arg constructor name", codes.SYNTAX)
 ARG_CONSTRUCTOR_TOO_MANY_ARGS: Final = ErrorMessage(
diff --git a/test-data/unit/check-classes.test b/test-data/unit/check-classes.test
index 7fd96f9abf94..c458b59ba7d2 100644
--- a/test-data/unit/check-classes.test
+++ b/test-data/unit/check-classes.test
@@ -7836,7 +7836,7 @@ def to_same_callable(fn: Callable[P, T]) -> Callable[P, T]:
 class A:
     def undecorated() -> None: ...  # E: Method must have at least one argument. Did you forget the "self" argument?
 
-    def undecorated_not_self(x: int) -> None: ...  # E: Self argument missing for a non-static method (or an invalid type for self)
+    def undecorated_not_self(x: int) -> None: ...  # E: self parameter missing for a non-static method (or an invalid type for self)
 
     def undecorated_not_self_2(self: int) -> None: ...  # E: The erased type of self "builtins.int" is not a supertype of its class "__main__.A"
 
@@ -7864,7 +7864,7 @@ class A:
     def g1() -> None: ...  # E: Method must have at least one argument. Did you forget the "self" argument?
 
     @to_same_callable
-    def g2(x: int) -> None: ...  # E: Self argument missing for a non-static method (or an invalid type for self)
+    def g2(x: int) -> None: ...  # E: self parameter missing for a non-static method (or an invalid type for self)
 
     @to_same_callable
     def g3(self: int) -> None: ...  # E: The erased type of self "builtins.int" is not a supertype of its class "__main__.A"
@@ -7909,7 +7909,7 @@ class A:
         return 0
 
     @to_same_callable
-    def fn2(_x: int) -> int:  # E: Self argument missing for a non-static method (or an invalid type for self)
+    def fn2(_x: int) -> int:  # E: self parameter missing for a non-static method (or an invalid type for self)
         return 0
 
     @to_same_callable
@@ -7931,7 +7931,7 @@ class B:
         return 0
 
     @remove_first
-    def fn3(self, _x: int) -> int:  # E: Self argument missing for a non-static method (or an invalid type for self)
+    def fn3(self, _x: int) -> int:  # E: self parameter missing for a non-static method (or an invalid type for self)
         return 0
 
     @remove_first
@@ -7965,15 +7965,15 @@ reveal_type(C().fn3)  # N: Revealed type is "def (self: __main__.C, _x: builtins
 
 class D:
     @add_wrong_first
-    def fn1() -> int:  # E: Self argument missing for a non-static method (or an invalid type for self)
+    def fn1() -> int:  # E: self parameter missing for a non-static method (or an invalid type for self)
         return 0
 
     @add_wrong_first
-    def fn2(_x: int) -> int:  # E: Self argument missing for a non-static method (or an invalid type for self)
+    def fn2(_x: int) -> int:  # E: self parameter missing for a non-static method (or an invalid type for self)
         return 0
 
     @add_wrong_first
-    def fn3(self, _x: int) -> int:  # E: Self argument missing for a non-static method (or an invalid type for self)
+    def fn3(self, _x: int) -> int:  # E: self parameter missing for a non-static method (or an invalid type for self)
         return 0
 
 reveal_type(D().fn1)  # E: Invalid self argument "D" to attribute function "fn1" with type "Callable[[int], int]" \
@@ -7996,7 +7996,7 @@ def to_same_callable(fn: Callable[P, T]) -> Callable[P, T]:
 def unchecked():
     class Bad:
         def fn() -> None: ...  # E: Method must have at least one argument. Did you forget the "self" argument?
-        def fn2(x: int) -> None: ...  # E: Self argument missing for a non-static method (or an invalid type for self)
+        def fn2(x: int) -> None: ...  # E: self parameter missing for a non-static method (or an invalid type for self)
 
         # TODO: would be nice to make this error, but now we see the func
         # being decorated as Any, not as a callable
@@ -8017,12 +8017,12 @@ def unchecked():
 def checked() -> None:
     class Bad:
         def fn() -> None: ...  # E: Method must have at least one argument. Did you forget the "self" argument?
-        def fn2(x: int) -> None: ...  # E: Self argument missing for a non-static method (or an invalid type for self)
+        def fn2(x: int) -> None: ...  # E: self parameter missing for a non-static method (or an invalid type for self)
 
         @to_same_callable
         def g() -> None: ...  # E: Method must have at least one argument. Did you forget the "self" argument?
         @to_same_callable
-        def g2(x: int) -> None: ...  # E: Self argument missing for a non-static method (or an invalid type for self)
+        def g2(x: int) -> None: ...  # E: self parameter missing for a non-static method (or an invalid type for self)
 
     class AlsoBad:
         def fn(): ...  # E: Method must have at least one argument. Did you forget the "self" argument?
diff --git a/test-data/unit/check-columns.test b/test-data/unit/check-columns.test
index 8458f0ac27dc..7509fb2d12d9 100644
--- a/test-data/unit/check-columns.test
+++ b/test-data/unit/check-columns.test
@@ -298,7 +298,7 @@ x = cast(int, y) # E:5: Redundant cast to "int"
 
 [case testColumnTypeSignatureHasTooFewArguments]
 if int():
-    def f(x, y): # E:5: Type signature has too few arguments
+    def f(x, y): # E:5: Type signature has too few parameters
         # type: (int) -> None
         pass
 
diff --git a/test-data/unit/check-errorcodes.test b/test-data/unit/check-errorcodes.test
index 58f48144b3e5..26831a091f53 100644
--- a/test-data/unit/check-errorcodes.test
+++ b/test-data/unit/check-errorcodes.test
@@ -38,7 +38,7 @@ main:1: error: Invalid syntax  [syntax]
 main:1: error: Invalid syntax. Perhaps you forgot a comma?  [syntax]
 
 [case testErrorCodeSyntaxError2]
-def f(): # E: Type signature has too many arguments  [syntax]
+def f(): # E: Type signature has too many parameters  [syntax]
     # type: (int) -> None
     1
 
@@ -382,7 +382,7 @@ def f(x):  # E: Function is missing a type annotation  [no-untyped-def]
 def g(x: int):  # E: Function is missing a return type annotation  [no-untyped-def]
     pass
 
-def h(x) -> None:  # E: Function is missing a type annotation for one or more arguments  [no-untyped-def]
+def h(x) -> None:  # E: Function is missing a type annotation for one or more parameters  [no-untyped-def]
     pass
 
 def gen():  # E: Function is missing a return type annotation  [no-untyped-def]
@@ -545,11 +545,11 @@ from typing import cast
 x = cast(int, int())  # E: Redundant cast to "int"  [redundant-cast]
 
 [case testErrorCodeInvalidCommentSignature]
-def f(x):  # E: Type signature has too few arguments  [syntax]
+def f(x):  # E: Type signature has too few parameters  [syntax]
     # type: () -> None
     pass
 
-def g(x):  # E: Type signature has too many arguments  [syntax]
+def g(x):  # E: Type signature has too many parameters  [syntax]
     # type: (int, int) -> None
     pass
 
diff --git a/test-data/unit/check-fastparse.test b/test-data/unit/check-fastparse.test
index f1c0716e9fb8..4eef7a0e116c 100644
--- a/test-data/unit/check-fastparse.test
+++ b/test-data/unit/check-fastparse.test
@@ -178,7 +178,7 @@ def f(*,
 [out]
 
 [case testFasterParseTooManyArgumentsAnnotation]
-def f():  # E: Type signature has too many arguments
+def f():  # E: Type signature has too many parameters
     # type: (int) -> None
     pass
 
@@ -186,7 +186,7 @@ f()
 f(1) # E: Too many arguments for "f"
 
 [case testFasterParseTooFewArgumentsAnnotation]
-def f(x, y):  # E: Type signature has too few arguments
+def f(x, y):  # E: Type signature has too few parameters
     # type: (int) -> None
     x()
     y()
@@ -215,10 +215,10 @@ x @ 1
 x @= 1
 
 [case testFastParserShowsMultipleErrors]
-def f(x):  # E: Type signature has too few arguments
+def f(x):  # E: Type signature has too few parameters
     # type: () -> None
     pass
-def g():  # E: Type signature has too many arguments
+def g():  # E: Type signature has too many parameters
     # type: (int) -> None
     pass
 
diff --git a/test-data/unit/check-flags.test b/test-data/unit/check-flags.test
index 94aae547882f..5c77a3e81f0d 100644
--- a/test-data/unit/check-flags.test
+++ b/test-data/unit/check-flags.test
@@ -8,7 +8,7 @@ main:2: error: Function is missing a type annotation
 # flags: --disallow-untyped-defs
 def f(x) -> int: pass
 [out]
-main:2: error: Function is missing a type annotation for one or more arguments
+main:2: error: Function is missing a type annotation for one or more parameters
 
 [case testNoArgumentFunction]
 # flags: --disallow-untyped-defs
@@ -63,7 +63,7 @@ async def f():  # E: Function is missing a return type annotation \
 
 [case testAsyncUnannotatedArgument]
 # flags: --disallow-untyped-defs
-async def f(x) -> None:  # E: Function is missing a type annotation for one or more arguments
+async def f(x) -> None:  # E: Function is missing a type annotation for one or more parameters
     pass
 [builtins fixtures/async_await.pyi]
 [typing fixtures/typing-async.pyi]
@@ -830,7 +830,7 @@ import standard, incomplete
 def incomplete(x) -> int:
     return 0
 [file incomplete.py]
-def incomplete(x) -> int:  # E: Function is missing a type annotation for one or more arguments
+def incomplete(x) -> int:  # E: Function is missing a type annotation for one or more parameters
     return 0
 [file mypy.ini]
 \[mypy]
@@ -847,7 +847,7 @@ import standard, incomplete
 def incomplete(x) -> int:
     return 0
 [file incomplete.py]
-def incomplete(x) -> int:  # E: Function is missing a type annotation for one or more arguments
+def incomplete(x) -> int:  # E: Function is missing a type annotation for one or more parameters
     return 0
 [file pyproject.toml]
 \[tool.mypy]
@@ -1555,7 +1555,7 @@ def g(m: Movie) -> Movie:
 
 def f(i: int):  # E: Function is missing a return type annotation
     pass
-def g(i) -> None:  # E: Function is missing a type annotation for one or more arguments
+def g(i) -> None:  # E: Function is missing a type annotation for one or more parameters
     pass
 def h(i: int) -> int:  # no error
     return i
@@ -1582,7 +1582,7 @@ def f(i: int, s):
 
 [out]
 main:3: error: Function is missing a return type annotation
-main:3: error: Function is missing a type annotation for one or more arguments
+main:3: error: Function is missing a type annotation for one or more parameters
 
 [case testDisallowIncompleteDefsAttrsNoAnnotations]
 # flags: --disallow-incomplete-defs
@@ -1609,7 +1609,7 @@ class Annotated:
 import attrs
 
 @attrs.define
-class PartiallyAnnotated:  # E: Function is missing a type annotation for one or more arguments
+class PartiallyAnnotated:  # E: Function is missing a type annotation for one or more parameters
     bar: int = attrs.field()
     baz = attrs.field()
 
diff --git a/test-data/unit/check-functions.test b/test-data/unit/check-functions.test
index a0762ab78f48..8ce971580714 100644
--- a/test-data/unit/check-functions.test
+++ b/test-data/unit/check-functions.test
@@ -778,7 +778,7 @@ main:8: error: Argument 1 to "g" has incompatible type "A"; expected "int"
 class A:
     def f(self):
         # type: () -> None
-        def g(x):  # E: Type signature has too few arguments
+        def g(x):  # E: Type signature has too few parameters
             # type: () -> None
             pass
 
@@ -802,7 +802,7 @@ class A:
         class B:
             def g(self):
                 # type: () -> None
-                def h(x):  # E: Type signature has too few arguments
+                def h(x):  # E: Type signature has too few parameters
                     # type: () -> None
                     pass
 
@@ -2143,13 +2143,13 @@ class A:
 def f(x, y, z): # type: (..., int) -> None
     pass
 [out]
-main:1: error: Ellipses cannot accompany other argument types in function type signature
+main:1: error: Ellipses cannot accompany other parameter types in function type signature
 
 [case testEllipsisWithSomethingBeforeItFails]
 def f(x, y, z): # type: (int, ...) -> None
     pass
 [out]
-main:1: error: Ellipses cannot accompany other argument types in function type signature
+main:1: error: Ellipses cannot accompany other parameter types in function type signature
 
 [case testRejectCovariantArgument]
 from typing import TypeVar, Generic
diff --git a/test-data/unit/check-overloading.test b/test-data/unit/check-overloading.test
index 5a445c818218..0d9ce42f148f 100644
--- a/test-data/unit/check-overloading.test
+++ b/test-data/unit/check-overloading.test
@@ -4347,7 +4347,7 @@ class Wrapper2:
     @staticmethod
     def foo(x: int) -> int: ...
     @overload
-    def foo(x: str) -> str: ...  # E: Self argument missing for a non-static method (or an invalid type for self)
+    def foo(x: str) -> str: ...  # E: self parameter missing for a non-static method (or an invalid type for self)
     @staticmethod
     def foo(x): pass
 
@@ -4358,7 +4358,7 @@ class Wrapper3:
     @overload
     @staticmethod
     def foo(x: str) -> str: ...
-    def foo(x: Union[int, str]): pass  # E: Self argument missing for a non-static method (or an invalid type for self)
+    def foo(x: Union[int, str]): pass  # E: self parameter missing for a non-static method (or an invalid type for self)
 [builtins fixtures/staticmethod.pyi]
 
 [case testOverloadWithSwappedDecorators2]
@@ -4394,7 +4394,7 @@ class Wrapper3:
     def foo(x: int) -> int: ...
 
     @overload
-    def foo(x: str) -> str: ...  # E: Self argument missing for a non-static method (or an invalid type for self)
+    def foo(x: str) -> str: ...  # E: self parameter missing for a non-static method (or an invalid type for self)
 
     @staticmethod
     def foo(x): pass
diff --git a/test-data/unit/check-python38.test b/test-data/unit/check-python38.test
index 595ff95f44dc..55895e9c6c2b 100644
--- a/test-data/unit/check-python38.test
+++ b/test-data/unit/check-python38.test
@@ -116,7 +116,7 @@ def g(x: int): ...
 
 [case testPEP570ArgTypesMissing]
 # flags: --disallow-untyped-defs
-def f(arg, /) -> None: ...  # E: Function is missing a type annotation for one or more arguments
+def f(arg, /) -> None: ...  # E: Function is missing a type annotation for one or more parameters
 
 [case testPEP570ArgTypesBadDefault]
 def f(arg: int = "ERROR", /) -> None: ...  # E: Incompatible default for argument "arg" (default has type "str", argument has type "int")
diff --git a/test-data/unit/check-selftype.test b/test-data/unit/check-selftype.test
index fe1c903f06ea..afed3fcb65c1 100644
--- a/test-data/unit/check-selftype.test
+++ b/test-data/unit/check-selftype.test
@@ -1058,7 +1058,7 @@ class A:
     def f(x: int) -> None: ...
     def g(self: None) -> None: ...
 [out]
-main:3: error: Self argument missing for a non-static method (or an invalid type for self)
+main:3: error: self parameter missing for a non-static method (or an invalid type for self)
 main:4: error: The erased type of self "None" is not a supertype of its class "__main__.A"
 
 [case testUnionPropertyField]
diff --git a/test-data/unit/fine-grained.test b/test-data/unit/fine-grained.test
index 41fb0ed18ba8..bb9ace3e2670 100644
--- a/test-data/unit/fine-grained.test
+++ b/test-data/unit/fine-grained.test
@@ -9124,15 +9124,15 @@ x = ''
 x = 1
 
 [out]
-c.py:1: error: Type signature has too few arguments
-a.py:1: error: Type signature has too few arguments
-a.py:5: error: Type signature has too few arguments
-a.py:11: error: Type signature has too few arguments
-==
-c.py:1: error: Type signature has too few arguments
-a.py:1: error: Type signature has too few arguments
-a.py:5: error: Type signature has too few arguments
-a.py:11: error: Type signature has too few arguments
+c.py:1: error: Type signature has too few parameters
+a.py:1: error: Type signature has too few parameters
+a.py:5: error: Type signature has too few parameters
+a.py:11: error: Type signature has too few parameters
+==
+c.py:1: error: Type signature has too few parameters
+a.py:1: error: Type signature has too few parameters
+a.py:5: error: Type signature has too few parameters
+a.py:11: error: Type signature has too few parameters
 
 [case testErrorReportingNewAnalyzer]
 # flags: --disallow-any-generics
diff --git a/test-data/unit/parse-errors.test b/test-data/unit/parse-errors.test
index 99baf519e31c..1eb3fbf8cba7 100644
--- a/test-data/unit/parse-errors.test
+++ b/test-data/unit/parse-errors.test
@@ -248,13 +248,13 @@ file:1: error: Function has duplicate type signatures
 def f(x, y): # type: (X, Y, Z) -> z
   pass
 [out]
-file:1: error: Type signature has too many arguments
+file:1: error: Type signature has too many parameters
 
 [case testTooFewTypes]
 def f(x, y): # type: (X) -> z
   pass
 [out]
-file:1: error: Type signature has too few arguments
+file:1: error: Type signature has too few parameters
 
 [case testCommentFunctionAnnotationVarArgMispatch-skip]
 # see mypy issue #1997
diff --git a/test-data/unit/semanal-errors.test b/test-data/unit/semanal-errors.test
index b69d35ce030e..40db0537c413 100644
--- a/test-data/unit/semanal-errors.test
+++ b/test-data/unit/semanal-errors.test
@@ -1158,8 +1158,8 @@ def f(): # type: (int) -> int
 def g(x): # type: () -> int
   pass
 [out]
-main:2: error: Type signature has too many arguments
-main:4: error: Type signature has too few arguments
+main:2: error: Type signature has too many parameters
+main:4: error: Type signature has too few parameters
 
 [case testStaticmethodAndNonMethod]
 import typing