Meaning of gonopodium

gon•o•po•di•um

Pronunciation: (gon"u-pō'dē-um), [key]
— pl. -po•di•a
  1. the modified anal fin of a male poeciliid fish, serving as an organ of copulation.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.