Tap, n.
 1. A hole or pipe through which liquor is drawn.
 2. A plug or spile for stopping a hole pierced in a cask, or the like; a faucet.
 3. Liquor drawn through a tap; hence, a certain kind or quality of liquor; as, a liquor of the same tap. [Colloq.]
 4. A place where liquor is drawn for drinking; a taproom; a bar. [Colloq.]
 5. Mech. A tool for forming an internal screw, as in a nut, consisting of a hardened steel male screw grooved longitudinally so as to have cutting edges.
 On tap. (a) Ready to be drawn; as, ale on tap. (b) Broached, or furnished with a tap; as, a barrel on tap.
 Plug tap Mech., a screw-cutting tap with a slightly tapering end.
 Tap bolt, a bolt with a head on one end and a thread on the other end, to be screwed into some fixed part, instead of passing through the part and receiving a nut. See Illust. under Bolt.
 Tap cinder Metal., the slag of a puddling furnace.