nipple Definition

1. The deep-coloured pointed projection on a breast, in the female the outlet of the ducts from which the young suck milk.

Thesaurus: pap, teat, mamilla, papilla, dug, tit.
(N Amer)
2. The teat on a baby's feeding-bottle.
3. mech.
Any small projection with a hole through which a flow is regulated or machine parts lubricated.