pin·nu·la \ˈpinyələ\noun (pluralpinnu·lae \-ˌlē, -ˌlī\) Etymology: New Latin, from Latin, small feather, small fin, from pinna feather, wing, fin, alteration of penna feather, wing — more at pen 1.: pinnule 2, 3 2.: a barb of a feather • pin·nu·lar\-_lə(r)\adjective