Source : Webster's Revised Unabridged Dictionary (1913)

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.