deep, distant
窵 centers on depth and remoteness: something physically deep, far away, or hard to reach. The two given meanings are closely linked by the idea of a large, empty space that creates distance.
窵 combines 穴 (hole, cavity) with 鳥 (bird), likely to express the idea of a deep, distant place such as a bird's nest hidden in a deep hole. The exact historical development is uncertain, but the components suggest depth and remoteness.
A bird 鳥 deep inside a cave 穴: the bird's nest is far away and hard to reach, so 窵 means deep and distant.
For チョウ, imagine a bird 鳥 deep in a hole 穴, and you call it a 'chou' (like the first part of 'chow') because it's so deep you can't see it: chou -> チョウ.