nipple

Etymology

From earlier neple, nypil, neble, believed to be a diminutive of nib, neb (“tip, point”), equivalent to nib + -le. Compare Old English nypel (“elephant trunk”), formed analogously as "a protuberance from one's neb" .

noun

1. (anatomy) The projection of a mammary gland from which, on female mammals, milk is secreted.
2. A mechanical device through which liquids or gases can be passed in a regulated manner.
3. An artificial nipple (definition 1) used for bottle-feeding infants.
4. Any small physical protrusion, such as the lumps on the F and J keys on computer keyboards.
5. Any small physical protrusion on an automotive, a machine part or any other part that fits into a groove on another part.
6. (now chiefly historical) A perforated segment that fits into part of the breech of a muzzle-loading gun, on which the percussion cap is fixed.
   I could tell he didn't agree but he went to the corner and took up his squirrel gun, feeling the nipple for a percussion cap. 2013, Philipp Meyer, The Son, Simon & Schuster, published 2014, page 23
7. (plumbing, chiefly US) A short tube threaded at both ends, used as a connector.
8. (cycling) An internally threaded piece which holds a bicycle spoke in place on the rim.
   Turn the nipples on to the bicycle spokes only one turn, for each spoke on the new wheel all the way around until they are all snug, then check alignment.
9. (computing, humorous) A pointing stick.

verb

1. (transitive) To fit (a baby's bottle, etc.) with a nipple.
2. (transitive) To give one's nipple to (a baby) to allow breastfeeding.