diff --git a/aiohttp/abc.py b/aiohttp/abc.py
index a21e6b5d0bd..bd448ed8abd 100644
--- a/aiohttp/abc.py
+++ b/aiohttp/abc.py
@@ -147,16 +147,10 @@ async def close(self) -> None:
         """Release resolver"""
 
 
-if TYPE_CHECKING:
-    IterableBase = Iterable[Morsel[str]]
-else:
-    IterableBase = Iterable
-
-
-ClearCookiePredicate = Callable[["Morsel[str]"], bool]
+ClearCookiePredicate = Callable[[Morsel[str]], bool]
 
 
-class AbstractCookieJar(Sized, IterableBase):
+class AbstractCookieJar(Sized, Iterable[Morsel[str]]):
     """Abstract Cookie Jar."""
 
     @property
diff --git a/aiohttp/client.py b/aiohttp/client.py
index dcbdd23dfd4..059f1adc401 100644
--- a/aiohttp/client.py
+++ b/aiohttp/client.py
@@ -24,7 +24,7 @@
 from typing import TYPE_CHECKING, Any, Final, Generic, TypedDict, TypeVar, final
 
 from multidict import CIMultiDict, MultiDict, MultiDictProxy, istr
-from yarl import URL
+from yarl import URL, Query
 
 from . import hdrs, http, payload
 from ._websocket.reader import WebSocketDataQueue
@@ -96,7 +96,7 @@
 from .http import WS_KEY, HttpVersion, WebSocketReader, WebSocketWriter
 from .http_websocket import WSHandshakeError, ws_ext_gen, ws_ext_parse
 from .tracing import Trace, TraceConfig
-from .typedefs import JSONEncoder, LooseCookies, LooseHeaders, Query, StrOrURL
+from .typedefs import JSONEncoder, LooseCookies, LooseHeaders, StrOrURL
 
 __all__ = (
     # client_exceptions
diff --git a/aiohttp/client_exceptions.py b/aiohttp/client_exceptions.py
index 7bff03171b2..af83a42705e 100644
--- a/aiohttp/client_exceptions.py
+++ b/aiohttp/client_exceptions.py
@@ -7,17 +7,12 @@
 
 from .typedefs import StrOrURL
 
-if TYPE_CHECKING:
+try:
     import ssl
 
     SSLContext = ssl.SSLContext
-else:
-    try:
-        import ssl
-
-        SSLContext = ssl.SSLContext
-    except ImportError:  # pragma: no cover
-        ssl = SSLContext = None  # type: ignore[assignment]
+except ImportError:  # pragma: no cover
+    ssl = SSLContext = None  # type: ignore[assignment]
 
 if TYPE_CHECKING:
     from .client_reqrep import ClientResponse, ConnectionKey, Fingerprint, RequestInfo
diff --git a/aiohttp/client_reqrep.py b/aiohttp/client_reqrep.py
index 0d6f435b6e5..551b3374c6a 100644
--- a/aiohttp/client_reqrep.py
+++ b/aiohttp/client_reqrep.py
@@ -14,7 +14,7 @@
 from typing import TYPE_CHECKING, Any, NamedTuple, TypedDict
 
 from multidict import CIMultiDict, CIMultiDictProxy, MultiDict, MultiDictProxy
-from yarl import URL
+from yarl import URL, Query
 
 from . import hdrs, multipart, payload
 from ._cookie_helpers import (
@@ -57,18 +57,14 @@
     StreamWriter,
 )
 from .streams import StreamReader
-from .typedefs import DEFAULT_JSON_DECODER, JSONDecoder, Query, RawHeaders
+from .typedefs import DEFAULT_JSON_DECODER, JSONDecoder, RawHeaders
 
-if TYPE_CHECKING:
+try:
     import ssl
     from ssl import SSLContext
-else:
-    try:
-        import ssl
-        from ssl import SSLContext
-    except ImportError:  # pragma: no cover
-        ssl = None  # type: ignore[assignment]
-        SSLContext = object  # type: ignore[misc,assignment]
+except ImportError:  # pragma: no cover
+    ssl = None  # type: ignore[assignment]
+    SSLContext = object  # type: ignore[misc,assignment]
 
 
 __all__ = ("ClientRequest", "ClientResponse", "RequestInfo", "Fingerprint")
diff --git a/aiohttp/connector.py b/aiohttp/connector.py
index 0b6081f8e08..b1820358bae 100644
--- a/aiohttp/connector.py
+++ b/aiohttp/connector.py
@@ -56,18 +56,13 @@
 else:
     Buffer = "bytes | bytearray | memoryview[int] | memoryview[bytes]"
 
-if TYPE_CHECKING:
+try:
     import ssl
 
     SSLContext = ssl.SSLContext
-else:
-    try:
-        import ssl
-
-        SSLContext = ssl.SSLContext
-    except ImportError:  # pragma: no cover
-        ssl = None  # type: ignore[assignment]
-        SSLContext = object  # type: ignore[misc,assignment]
+except ImportError:  # pragma: no cover
+    ssl = None  # type: ignore[assignment]
+    SSLContext = object  # type: ignore[misc,assignment]
 
 EMPTY_SCHEMA_SET = frozenset({""})
 HTTP_SCHEMA_SET = frozenset({"http", "https"})
diff --git a/aiohttp/http_exceptions.py b/aiohttp/http_exceptions.py
index 200cfeb3c68..544e1d03a25 100644
--- a/aiohttp/http_exceptions.py
+++ b/aiohttp/http_exceptions.py
@@ -2,7 +2,7 @@
 
 from textwrap import indent
 
-from .typedefs import _CIMultiDict
+from multidict import CIMultiDict
 
 __all__ = ("HttpProcessingError",)
 
@@ -26,7 +26,7 @@ def __init__(
         *,
         code: int | None = None,
         message: str = "",
-        headers: _CIMultiDict | None = None,
+        headers: CIMultiDict[str] | None = None,
     ) -> None:
         if code is not None:
             self.code = code
@@ -45,7 +45,9 @@ class BadHttpMessage(HttpProcessingError):
     code = 400
     message = "Bad Request"
 
-    def __init__(self, message: str, *, headers: _CIMultiDict | None = None) -> None:
+    def __init__(
+        self, message: str, *, headers: CIMultiDict[str] | None = None
+    ) -> None:
         super().__init__(message=message, headers=headers)
         self.args = (message,)
 
diff --git a/aiohttp/payload.py b/aiohttp/payload.py
index 2bce326ccb4..d5996a0e915 100644
--- a/aiohttp/payload.py
+++ b/aiohttp/payload.py
@@ -7,9 +7,9 @@
 import sys
 import warnings
 from abc import ABC, abstractmethod
-from collections.abc import Iterable
+from collections.abc import AsyncIterable, AsyncIterator, Iterable
 from itertools import chain
-from typing import IO, TYPE_CHECKING, Any, Final, TextIO
+from typing import IO, Any, Final, TextIO
 
 from multidict import CIMultiDict
 
@@ -23,7 +23,7 @@
     sentinel,
 )
 from .streams import StreamReader
-from .typedefs import JSONEncoder, _CIMultiDict
+from .typedefs import JSONEncoder
 
 __all__ = (
     "PAYLOAD_REGISTRY",
@@ -145,7 +145,7 @@ def __init__(
         self,
         value: Any,
         headers: (
-            _CIMultiDict | dict[str, str] | Iterable[tuple[str, str]] | None
+            CIMultiDict[str] | dict[str, str] | Iterable[tuple[str, str]] | None
         ) = None,
         content_type: None | str | _SENTINEL = sentinel,
         filename: str | None = None,
@@ -154,7 +154,7 @@ def __init__(
     ) -> None:
         self._encoding = encoding
         self._filename = filename
-        self._headers: _CIMultiDict = CIMultiDict()
+        self._headers = CIMultiDict[str]()
         self._value = value
         if content_type is not sentinel and content_type is not None:
             assert isinstance(content_type, str)
@@ -189,7 +189,7 @@ def filename(self) -> str | None:
         return self._filename
 
     @property
-    def headers(self) -> _CIMultiDict:
+    def headers(self) -> CIMultiDict[str]:
         """Custom item headers"""
         return self._headers
 
@@ -939,26 +939,14 @@ def __init__(
         )
 
 
-if TYPE_CHECKING:
-    from collections.abc import AsyncIterable, AsyncIterator
-
-    _AsyncIterator = AsyncIterator[bytes]
-    _AsyncIterable = AsyncIterable[bytes]
-else:
-    from collections.abc import AsyncIterable, AsyncIterator
-
-    _AsyncIterator = AsyncIterator
-    _AsyncIterable = AsyncIterable
-
-
 class AsyncIterablePayload(Payload):
-    _iter: _AsyncIterator | None = None
-    _value: _AsyncIterable
+    _iter: AsyncIterator[bytes] | None = None
+    _value: AsyncIterable[bytes]
     _cached_chunks: list[bytes] | None = None
     # _consumed stays False to allow reuse with cached content
     _autoclose = True  # Iterator doesn't need explicit closing
 
-    def __init__(self, value: _AsyncIterable, *args: Any, **kwargs: Any) -> None:
+    def __init__(self, value: AsyncIterable[bytes], *args: Any, **kwargs: Any) -> None:
         if not isinstance(value, AsyncIterable):
             raise TypeError(
                 "value argument must support "
diff --git a/aiohttp/typedefs.py b/aiohttp/typedefs.py
index dd7ad257460..cd016a4e3c4 100644
--- a/aiohttp/typedefs.py
+++ b/aiohttp/typedefs.py
@@ -1,52 +1,34 @@
 import json
 import os
 from collections.abc import Awaitable, Callable, Iterable, Mapping
-from typing import TYPE_CHECKING, Any, Protocol, Union
+from http.cookies import BaseCookie, Morsel
+from typing import TYPE_CHECKING, Any, Protocol
 
-from multidict import CIMultiDict, CIMultiDictProxy, MultiDict, MultiDictProxy, istr
-from yarl import URL, Query as _Query
-
-Query = _Query
+from multidict import CIMultiDict, CIMultiDictProxy, istr
+from yarl import URL
 
 DEFAULT_JSON_ENCODER = json.dumps
 DEFAULT_JSON_DECODER = json.loads
 
 if TYPE_CHECKING:
-    _CIMultiDict = CIMultiDict[str]
-    _CIMultiDictProxy = CIMultiDictProxy[str]
-    _MultiDict = MultiDict[str]
-    _MultiDictProxy = MultiDictProxy[str]
-    from http.cookies import BaseCookie, Morsel
-
     from .web import Request, StreamResponse
-else:
-    _CIMultiDict = CIMultiDict
-    _CIMultiDictProxy = CIMultiDictProxy
-    _MultiDict = MultiDict
-    _MultiDictProxy = MultiDictProxy
 
-Byteish = Union[bytes, bytearray, memoryview]
+Byteish = bytes | bytearray | memoryview
 JSONEncoder = Callable[[Any], str]
 JSONDecoder = Callable[[str], Any]
-LooseHeaders = Union[
-    Mapping[str, str],
-    Mapping[istr, str],
-    _CIMultiDict,
-    _CIMultiDictProxy,
-    Iterable[tuple[str | istr, str]],
-]
+LooseHeaders = (
+    Mapping[str, str]
+    | Mapping[istr, str]
+    | CIMultiDict[str]
+    | CIMultiDictProxy[str]
+    | Iterable[tuple[str | istr, str]]
+)
 RawHeaders = tuple[tuple[bytes, bytes], ...]
-StrOrURL = Union[str, URL]
-
-LooseCookiesMappings = Mapping[str, Union[str, "BaseCookie[str]", "Morsel[Any]"]]
-LooseCookiesIterables = Iterable[
-    tuple[str, Union[str, "BaseCookie[str]", "Morsel[Any]"]]
-]
-LooseCookies = Union[
-    LooseCookiesMappings,
-    LooseCookiesIterables,
-    "BaseCookie[str]",
-]
+StrOrURL = str | URL
+
+LooseCookiesMappings = Mapping[str, str | BaseCookie[str] | Morsel[Any]]
+LooseCookiesIterables = Iterable[tuple[str, str | BaseCookie[str] | Morsel[Any]]]
+LooseCookies = LooseCookiesMappings | LooseCookiesIterables | BaseCookie[str]
 
 Handler = Callable[["Request"], Awaitable["StreamResponse"]]
 
@@ -57,4 +39,4 @@ def __call__(
     ) -> Awaitable["StreamResponse"]: ...
 
 
-PathLike = Union[str, "os.PathLike[str]"]
+PathLike = str | os.PathLike[str]
diff --git a/aiohttp/web.py b/aiohttp/web.py
index be0797031a1..1322360cbed 100644
--- a/aiohttp/web.py
+++ b/aiohttp/web.py
@@ -8,7 +8,7 @@
 from collections.abc import Awaitable, Callable, Iterable, Iterable as TypingIterable
 from contextlib import suppress
 from importlib import import_module
-from typing import TYPE_CHECKING, Any, cast
+from typing import Any, cast
 
 from .abc import AbstractAccessLogger
 from .helpers import AppKey
@@ -256,13 +256,10 @@
 )
 
 
-if TYPE_CHECKING:
+try:
     from ssl import SSLContext
-else:
-    try:
-        from ssl import SSLContext
-    except ImportError:  # pragma: no cover
-        SSLContext = object  # type: ignore[misc,assignment]
+except ImportError:  # pragma: no cover
+    SSLContext = object  # type: ignore[misc,assignment]
 
 # Only display warning when using -Wdefault, -We, -X dev or similar.
 warnings.filterwarnings("ignore", category=NotAppKeyWarning, append=True)
diff --git a/aiohttp/web_app.py b/aiohttp/web_app.py
index bef158219e4..ddd30efb72f 100644
--- a/aiohttp/web_app.py
+++ b/aiohttp/web_app.py
@@ -12,7 +12,7 @@
     Sequence,
 )
 from functools import lru_cache, partial, update_wrapper
-from typing import TYPE_CHECKING, Any, TypeVar, cast, final, overload
+from typing import Any, TypeVar, cast, final, overload
 
 from aiosignal import Signal
 from frozenlist import FrozenList
@@ -39,21 +39,11 @@
 
 __all__ = ("Application", "CleanupError")
 
-
-if TYPE_CHECKING:
-    _AppSignal = Signal["Application"]
-    _RespPrepareSignal = Signal[Request, StreamResponse]
-    _Middlewares = FrozenList[Middleware]
-    _MiddlewaresHandlers = Sequence[Middleware]
-    _Subapps = list["Application"]
-else:
-    # No type checker mode, skip types
-    _AppSignal = Signal
-    _RespPrepareSignal = Signal
-    _Handler = Callable
-    _Middlewares = FrozenList
-    _MiddlewaresHandlers = Sequence
-    _Subapps = list
+_AppSignal = Signal["Application"]
+_RespPrepareSignal = Signal[Request, StreamResponse]
+_Middlewares = FrozenList[Middleware]
+_MiddlewaresHandlers = Sequence[Middleware]
+_Subapps = list["Application"]
 
 _T = TypeVar("_T")
 _U = TypeVar("_U")
@@ -415,10 +405,7 @@ def exceptions(self) -> list[BaseException]:
         return cast(list[BaseException], self.args[1])
 
 
-if TYPE_CHECKING:
-    _CleanupContextBase = FrozenList[Callable[[Application], AsyncIterator[None]]]
-else:
-    _CleanupContextBase = FrozenList
+_CleanupContextBase = FrozenList[Callable[[Application], AsyncIterator[None]]]
 
 
 class CleanupContext(_CleanupContextBase):
diff --git a/aiohttp/web_response.py b/aiohttp/web_response.py
index 2f921d4f559..2d09f82c225 100644
--- a/aiohttp/web_response.py
+++ b/aiohttp/web_response.py
@@ -1,5 +1,4 @@
 import asyncio
-import collections.abc
 import datetime
 import enum
 import json
@@ -43,10 +42,6 @@
 if TYPE_CHECKING:
     from .web_request import BaseRequest
 
-    BaseClass = MutableMapping[str, Any]
-else:
-    BaseClass = collections.abc.MutableMapping
-
 
 # TODO(py311): Convert to StrEnum for wider use
 class ContentCoding(enum.Enum):
@@ -66,7 +61,7 @@ class ContentCoding(enum.Enum):
 ############################################################
 
 
-class StreamResponse(BaseClass, HeadersMixin, CookieMixin):
+class StreamResponse(MutableMapping[str, Any], HeadersMixin, CookieMixin):
 
     _body: None | bytes | bytearray | Payload
     _length_check = True
diff --git a/aiohttp/web_runner.py b/aiohttp/web_runner.py
index b06c9ebce94..0b04c317f93 100644
--- a/aiohttp/web_runner.py
+++ b/aiohttp/web_runner.py
@@ -2,7 +2,7 @@
 import signal
 import socket
 from abc import ABC, abstractmethod
-from typing import TYPE_CHECKING, Any, Generic, TypeVar
+from typing import Any, Generic, TypeVar
 
 from yarl import URL
 
@@ -16,13 +16,10 @@
 from .web_request import BaseRequest, Request
 from .web_server import Server
 
-if TYPE_CHECKING:
+try:
     from ssl import SSLContext
-else:
-    try:
-        from ssl import SSLContext
-    except ImportError:  # pragma: no cover
-        SSLContext = object  # type: ignore[misc,assignment]
+except ImportError:  # pragma: no cover
+    SSLContext = object  # type: ignore[misc,assignment]
 
 __all__ = (
     "BaseSite",
diff --git a/aiohttp/web_urldispatcher.py b/aiohttp/web_urldispatcher.py
index 2642ed6542e..e4b3f2f34fe 100644
--- a/aiohttp/web_urldispatcher.py
+++ b/aiohttp/web_urldispatcher.py
@@ -60,10 +60,6 @@
 if TYPE_CHECKING:
     from .web_app import Application
 
-    BaseDict = dict[str, str]
-else:
-    BaseDict = dict
-
 CIRCULAR_SYMLINK_ERROR = (RuntimeError,) if sys.version_info < (3, 13) else ()
 
 HTTP_METHOD_RE: Final[Pattern[str]] = re.compile(
@@ -212,7 +208,7 @@ async def handle_expect_header(self, request: Request) -> StreamResponse | None:
         return await self._expect_handler(request)
 
 
-class UrlMappingMatchInfo(BaseDict, AbstractMatchInfo):
+class UrlMappingMatchInfo(dict[str, str], AbstractMatchInfo):
 
     __slots__ = ("_route", "_apps", "_current_app", "_frozen")
 
diff --git a/aiohttp/worker.py b/aiohttp/worker.py
index da44d7253fc..375ac32e77f 100644
--- a/aiohttp/worker.py
+++ b/aiohttp/worker.py
@@ -7,7 +7,7 @@
 import signal
 import sys
 from types import FrameType
-from typing import TYPE_CHECKING, Any, Optional
+from typing import Any, Optional
 
 from gunicorn.config import AccessLogFormat as GunicornAccessLogFormat
 from gunicorn.workers import base
@@ -18,18 +18,13 @@
 from .web_app import Application
 from .web_log import AccessLogger
 
-if TYPE_CHECKING:
+try:
     import ssl
 
     SSLContext = ssl.SSLContext
-else:
-    try:
-        import ssl
-
-        SSLContext = ssl.SSLContext
-    except ImportError:  # pragma: no cover
-        ssl = None  # type: ignore[assignment]
-        SSLContext = object  # type: ignore[misc,assignment]
+except ImportError:  # pragma: no cover
+    ssl = None  # type: ignore[assignment]
+    SSLContext = object  # type: ignore[misc,assignment]
 
 
 __all__ = ("GunicornWebWorker", "GunicornUVLoopWebWorker")
diff --git a/tests/test_client_functional.py b/tests/test_client_functional.py
index e4242c6d117..473427278f8 100644
--- a/tests/test_client_functional.py
+++ b/tests/test_client_functional.py
@@ -22,7 +22,7 @@
 import trustme
 from multidict import MultiDict
 from pytest_mock import MockerFixture
-from yarl import URL
+from yarl import URL, Query
 
 import aiohttp
 from aiohttp import Fingerprint, ServerFingerprintMismatch, hdrs, payload, web
@@ -48,7 +48,7 @@
 )
 from aiohttp.pytest_plugin import AiohttpClient, AiohttpServer
 from aiohttp.test_utils import TestClient, TestServer, unused_port
-from aiohttp.typedefs import Handler, Query
+from aiohttp.typedefs import Handler
 
 
 @pytest.fixture(autouse=True)