noun
Refers to the pod of legumes like peas and beans, or the shell/hull of certain seeds.
枝豆のさやをむいて、中の豆を取り出す。
Shell the edamame pods and take out the beans inside.
この豆はさやごと食べられます。
These beans can be eaten pod and all.
The origin is uncertain; it is a native Japanese word (和語). The kanji 莢 is a Chinese character meaning 'pod' and is used here as a semantic match, not reflecting a Chinese borrowing.