nipple

中文： 乳头、奶头、奶嘴

1. The projection of a mammary gland from which, on female therian mammals, milk is secreted.
2. The nipple (noun sense 1) and the areola together.
3. A mechanical device through which liquids or gases can be passed in a regulated manner.
4. An artificial nipple (noun sense 1) used for bottle-feeding infants.
5. Any small physical protrusion, such as the lumps on the F and J keys on computer keyboards.
6. Any small physical protrusion on an automotive, a machine part or any other part that fits into a groove on another part.
7. A perforated segment that fits into part of the breech of a muzzle-loading gun, on which the percussion cap is fixed.
8. A short tube threaded at both ends, used as a connector. (US)

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