Meaning of nephridium

ne•phrid•i•um

Pronunciation: (nu-frid'ē-um), [key]
— pl. -phrid•i•a
  1. the excretory organ of many invertebrates, consisting of a tubule with one end opening into the body cavity and the other opening into a pore at the body surface.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.