Pin"nule (?), n. [L. pinnula, dim. of pinna feather: cf. F. pinnule.] 1. (Bot.) One of the small divisions of a decompound frond or leaf. See Illust. of Bipinnate leaf, under Bipinnate.

2. (Zoöl.) Any one of a series of small, slender organs, or parts, when arranged in rows so as to have a plumelike appearance; as, a pinnule of a gorgonia; the pinnules of a crinoid.