Source : Webster's Revised Unabridged Dictionary (1913)

Tap \Tap\, v. t. [imp. & p. p. {Tapped}; p. pr. & vb. n.
   {Tapping}.] [F. taper to strike; of Teutonic origin; cf.
   dial. G. tapp, tapps, a blow, tappe a paw, fist, G. tappen to
   grope.]
   1. To strike with a slight or gentle blow; to touch gently;
      to rap lightly; to pat; as, to tap one with the hand or a
      cane.

   2. To put a new sole or heel on; as, to tap shoes.

Source : WordNet®

tapping
     n : the sound of light blow or knock; "he heard the tapping of
         the man's cane"

tap
     v 1: cut a female screw thread with a tap
     2: draw from or dip into to get something; "tap one's memory";
        "tap a source of money"
     3: strike lightly; "He tapped me on the shoulder" [syn: {tip}]
     4: draw from; make good use of; "we must exploit the resources
        we are given wisely" [syn: {exploit}]
     5: tap a telephone or telegraph wire to get information; "The
        FBI was tapping the phone line of the suspected spy"; "Is
        this hotel room bugged?" [syn: {wiretap}, {intercept}, {bug}]
     6: furnish with a tap or spout, so as to be able to draw liquid
        from it; "tap a cask of wine"
     7: make light, repeated taps on a surface; "he was tapping his
        fingers on the table impatiently" [syn: {rap}, {knock}, {pink}]
     8: walk with a tapping sound
     9: dance and make rhythmic clicking sounds by means of metal
        plates nailed to the sole of the dance shoes; "Glover
        tapdances better than anybody" [syn: {tapdance}]
     10: draw (liquor) from a tap; "tap beer in a bar"
     11: pierce in order to draw a liquid from; "tap a maple tree for
         its syrup"; "tap a keg of beer"
     12: make a solicitation or entreaty for something; request
         urgently or persistently; "Henry IV solicited the Pope
         for a divorce"; "My neighbor keeps soliciting money for
         different charities" [syn: {solicit}, {beg}]
     [also: {tapping}, {tapped}]

tap
     n 1: the sound made by a gentle blow [syn: {pat}, {rap}]
     2: a faucet for drawing water from a pipe or cask [syn: {water
        faucet}, {water tap}, {spigot}, {hydrant}]
     3: a gentle blow [syn: {rap}, {strike}]
     4: a small metal plate that attaches to the toe or heel of a
        shoe (as in tap dancing)
     5: a tool for cutting female (internal) screw threads
     6: a plug for a bunghole in a cask [syn: {spigot}]
     7: the act of tapping a telephone or telegraph line to get
        information [syn: {wiretap}]
     8: a light touch or stroke [syn: {pat}, {dab}]
     [also: {tapping}, {tapped}]

tapping
     See {tap}