1. [n]  depression of a button on a computer mouse; "a click on the right button for example"
2. [n]  a hinged catch that fits into a notch of a ratchet to move a wheel forward or prevent it from moving backward
3. [n]  a stop consonant made by the suction of air into the mouth (as in Bantu)
4. [n]  a short light metallic sound
5. [v]  become clear or enter one's consciousness or emotions; "It dawned on him that she had betrayed him"; "she was penetrated with sorrow"
6. [v]  make a clucking sounds, characteristic of hens
7. [v]  produce a click; "Xhosa speakers click"
8. [v]  cause to make a snapping sound; of fingers
9. [v]  move or strike with a click; "then the brightness as he clicked on the light."
10. [v]  make a clicking or ticking sound; "The clock ticked away"
11. [v]  click repeatedly or uncontrollably, as of teeth

Click
Follows the life and career of the man who revolutionized photography by developing a camera simple enough for anyone to use

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1. \Click\, v. i. [imp. & p. p. {Clicked}; p. pr. & vb. n.
   {Clicking}.] [Prob. an onomatopoetic word: cf. OF. cliquier.
   {See Clack}, and cf. {Clink}, {Clique}.]
   To make a slight, sharp noise (or a succession of such
   noises), as by gentle striking; to tick.
         The varnished clock that clicked behind the door.
                                                  --Goldsmith.
   

2. \Click\, v. t.
   1. To move with the sound of a click.
            She clicked back the bolt which held the window
            sash.                                 --Thackeray.
   2. To cause to make a clicking noise, as by striking
      together, or against something.
            [Jove] clicked all his marble thumbs. --Ben Jonson.
            When merry milkmaids click the latch. --Tennyson.
   

3. \Click\, n.
   1. A slight sharp noise, such as is made by the cocking of a
      pistol.
   2. A kind of articulation used by the natives of Southern
      Africa, consisting in a sudden withdrawal of the end or
      some other portion of the tongue from a part of the mouth
      with which it is in contact, whereby a sharp, clicking
      sound is produced. The sounds are four in number, and are
      called cerebral, palatal, dental, and lateral clicks or
      clucks, the latter being the noise ordinarily used in
      urging a horse forward.
   

4. \Click\, v. t. [OE. kleken, clichen. Cf. {Clutch}.]
   To snatch. [Prov. Eng.] --Halliwell.
   

5. \Click\, n. [Cf. 4th {Click}, and OF. clique latch.]
   1. A detent, pawl, or ratchet, as that which catches the cogs
      of a ratchet wheel to prevent backward motion. See Illust.
      of {Ratched wheel}.
   2. The latch of a door. [Prov. Eng.]
   

To press and release a button on a mouse or other pointing device. This generates an event, also specifying the screen position, which is processed by the window manager or application program. On a mouse with more than one button, the unqualified term usually implies pressing the left-most button (with the right index finger), other buttons would be qualified, e.g. "right-click". Keyboard modifiers may also be used, e.g. "shift-click", meaning to hold down the shift key on the keyboard while clicking the mouse button.

If the mouse moves while the button is pressed then this is a drag.