pinnule

noun

1. Zoology.
   1. a part or organ resembling a barb of a feather, a fin, or the like.
   2. a finlet.
2. Botany. 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.

noun plural pinnules or pinnulae (ˈpɪnjʊˌliː)

1. any of the lobes of a leaflet of a pinnate compound leaf, which is itself pinnately divided
2. zoology any feather-like part, such as any of the arms of a sea lily

1. Any of the smaller leaflets into which each leaflet of a bipinnately compound leaf is subdivided. The leaves of many ferns are divided into pinnules.