Meaning of nematocyst

nem•a•to•cyst

Pronunciation: (nem'u-tu-sist", ni-mat'u-), [key]
— n. Zool.
  1. an organ in coelenterates consisting of a minute capsule containing an ejectable thread that causes a sting.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.