wings; pinion
Rare standalone noun; almost exclusively used in the compound 羽交い締め (はがいじめ, full nelson hold). The sense refers to a bird's wing or the pinion joint.
The 羽交い in 羽交い締め is an old word referring to the base of a bird's wing.
full nelson
Compound of 羽 (は, wing) and 交い (かい, crossing/joining), referring to the joint where the wing meets the body. The exact historical derivation is uncertain.