tap \tap\, n. as. taeppa, akin to d. tap, g. zapfen, ohg.
   zapfo, dan. tap, sw. tapp, icel. tappi. cf. tampion,
   tip.
   1. a hole or pipe through which liquor is drawn.
      1913 webster

   2. a plug or spile for stopping a hole pierced in a cask, or
      the like; a faucet.
      1913 webster

   3. liquor drawn through a tap; hence, a certain kind or
      quality of liquor; as, a liquor of the same tap. colloq.
      1913 webster

   4. a place where liquor is drawn for drinking; a taproom; a
      bar. colloq.
      1913 webster

   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.
      1913 webster

   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.
      1913 webster
see also:
tampion tip on tap plug tap tap bolt bolt 
tap cinder 

on tap
     adj 1: of liquids available by turning a tap; "ale on tap"; "hot
            and cold running water on tap" syn: on tapp
     2: available for immediate use; "extra personnel on tap";
        "other sports and entertainment facilities are on tap";
        "there are numerous projects on tap" syn: on tapp
see also:
on tapp