nip·ple (n?p??l)n.1. a. The small projection near the center of the mammary gland containing the outlets of the milk ducts through which young mammals obtain milk from the adult female; a teat.b. A corresponding projection of the male breast.2. a. The rubber cap on a bottle from which a baby nurses.b. A pacifier for an infant.3. Any of various devices functioning like or resembling a nipple, especially:a. A regulated opening for discharging a liquid, as in a small stopcock.b. A pipe coupling threaded on both ends.c. A short extension of pipe to which a nozzle can be attached.d. A small projection through which grease in a grease gun can be forced into a bearing.4. A natural or geographic projection resembling a nipple, as a mountain crest.[From obsolete neble, diminutive of neb.]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.nipple (?n?p?l) n1. (Anatomy) Also called: mamilla, papilla or teat the small conical projection in the centre of the areola of each breast, which in women contains the outlet of the milk ducts. 2. something resembling a nipple in shape or function3. (Mechanical Engineering) Also called: grease nipple a small drilled bush, usually screwed into a bearing, through which grease is introduced4. US and Canadian an informal word for dummy11[C16: from earlier neble, nible, perhaps from neb, nib]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014nip?ple (?n?p ?l) n. 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. [1520?30; earlier neble, nib(b)le, nepil; compare Dan nip point] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.nip·ple (n?p??l) A small projection near the center of the mammary gland, as of the human breast, containing in females the outlets of the milk ducts.The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.nippleThe conical projection on a breast, which contains the outlets of the milk ducts.Dictionary of Unfamiliar Words by Diagram Group Copyright © 2008 by Diagram Visual Information Limited