fifth degree (of the Japanese and Chinese pentatonic scale)
「羽」 has other readings with different meanings.
空に白い鳥が三羽仲良く飛んでいる。
Three white birds are flying together in the sky.
今朝森で兎を一羽捕まえて持ち帰った。
I caught a rabbit in the forest this morning and brought it home.
羽は鳥や兎を数えるときに使う助数詞だ。
The counter '羽' is used when counting birds and rabbits.