1530s, nyppell, "teat, duct-laden extremity of a mammalian breast," alteration of neble (1520s), probably diminutive of neb "bill, beak, snout" (see neb), hence, literally "a small projection." In reference to an artificial device on an infant's bottle, from 1875. A 16c.-17c. slang term for a woman's nipples was cherrilets.
nipple nip·ple (nĭp'əl)
The projection at the apex of the mammary gland, on the surface of which the lactiferous ducts open, surrounded by the circular pigmented areola. Also called mamilla, papilla mammae, teat, thelium.