nipple

UK: /ˈnɪp^əl/ US: /ˈnɪpəl/ ,(nip′əl)

WordReference Random House Learner's Dictionary of American English © 2025

nip•ple /ˈnɪpəl/   n. [countable]

1. Zoology the dark part of the breast where, in the female, milk is sucked by a baby;
   teat.
2. something resembling it, such as the mouthpiece of a nursing bottle or a pacifier.

WordReference Random House Unabridged Dictionary of American English © 2025

nip•ple  (nip′əl), 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; perh. akin to nib; compare Danish nip point; see -le

nip′ple•less, adj. 

Collins Concise English Dictionary © HarperCollins Publishers::

nipple / ˈnɪp^əl/ noun

1. Also called: mamilla, papilla, 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 function
3. Also called: grease nipple a small drilled bush, usually screwed into a bearing, through which grease is introduced
4. 
   an informal word for dummy11

Etymology: 16th Century: from earlier neble, nible, perhaps from neb, nib