Nipple \Nip"ple\, n. [Formerly neble, a dim. of neb. See Neb, Nib.]

1. (Anat.) The protuberance through which milk is drawn from the breast or mamma; the mammilla; a teat; a pap.

2. The orifice at which any animal liquid, as the oil from an oil bag, is discharged. [R.]

--Derham.

3. Any small projection or article in which there is an orifice for discharging a fluid, or for other purposes; as, the nipple of a nursing bottle; the nipple of a percussion lock, or that part on which the cap is put and through which the fire passes to the charge.

4. (Mech.) A pipe fitting, consisting of a short piece of pipe, usually provided with a screw thread at each end, for connecting two other fittings.

Solder nipple, a short pipe, usually of brass, one end of which is tapered and adapted for attachment to the end of a lead pipe by soldering.

Source: Webster's Revised Unabridged Dictionary (1913)