The small raised parts in the center of the breast; small rounded projections on objects like bottle tops or faucets.
From Middle English 'nible' or 'nipil,' diminutive of 'nip,' possibly from Old English. The term extends to any small protruding point on objects.
The word 'nipple' originally referred to small protrusions on anything, and people applied it to bottle tops, faucets, and machines before it meant the body part. It shows how body words often come from comparing things to objects we see.
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