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. (Science: mechanics) 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.
Origin: Formerly neble, a dim. Of neb. See Neb, Nib. The small projection of a mammary gland.The projection of the [[mammary gland that allows the young access to the [[milk inside them.