Definition of "nipple"

(anatomy) The projection of a mammary gland from which, on female mammals, milk is secreted.  examples

A mechanical device through which liquids or gases can be passed in a regulated manner.  examples

An artificial nipple (definition 1) used for bottle-feeding infants.  examples

Any small physical protrusion, such as the lumps on the F and J keys on computer keyboards.  examples

Any small physical protrusion on an automotive, a machine part or any other part that fits into a groove on another part.  examples

(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.  quotations

(plumbing, chiefly US) A short tube threaded at both ends, used as a connector.  examples

(cycling) An internally threaded piece which holds a bicycle spoke in place on the rim.  examples

(computing, humorous) A pointing stick.  examples

(transitive) To fit (a baby's bottle, etc.) with a nipple.  examples

(transitive) To give one's nipple to (a baby) to allow breastfeeding.  examples