Pronunciation: (pin'yOOl),[key] —n. 1. Zool. a. a part or organ resembling a barb of a feather, a fin, or the like.
b. a finlet.
2. Bot.a secondary pinna, one of the pinnately disposed divisions of a bipinnate leaf.
3. a metal plate with a small hole in it, used as a sight in a quadrant.