Pronunciation: (nip'ul), [key]
1. a protuberance of the mamma or breast where, in the female, the milk ducts discharge; teat.
2. something resembling it, as the mouthpiece of a nursing bottle or pacifier.
3. a short piece of pipe with threads on each end, used for joining valves.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.