nipple

n. 1 small projection in which the mammary ducts of either sex of mammals terminate and from which in females milk is secreted for the young. 2 teat of a feeding-bottle. 3 device like a nipple in function. 4 nipple-like protuberance. [perhaps from neb tip]

n. The protuberance through which milk is drawn from the breast or mamma; the mammilla; a teat; a pap.