Source : Webster's Revised Unabridged Dictionary (1913)

Button \But"ton\, n. [OE. boton, botoun, F. bouton button, bud,
   prop. something pushing out, fr. bouter to push. See {Butt}
   an end.]
   1. A knob; a small ball; a small, roundish mass.

   2. A catch, of various forms and materials, used to fasten
      together the different parts of dress, by being attached
      to one part, and passing through a slit, called a
      buttonhole, in the other; -- used also for ornament.

   3. A bud; a germ of a plant. --Shak.

   4. A piece of wood or metal, usually flat and elongated,
      turning on a nail or screw, to fasten something, as a
      door.

   5. A globule of metal remaining on an assay cupel or in a
      crucible, after fusion.

   {Button hook}, a hook for catching a button and drawing it
      through a buttonhole, as in buttoning boots and gloves.

   {Button shell} (Zo["o]l.), a small, univalve marine shell of
      the genus {Rotella}.

   {Button snakeroot}. (Bot.)
      (a) The American composite genus {Liatris}, having rounded
          buttonlike heads of flowers.
      (b) An American umbelliferous plant with rigid, narrow
          leaves, and flowers in dense heads.

   {Button tree} (Bot.), a genus of trees ({Conocarpus}),
      furnishing durable timber, mostly natives of the West
      Indies.

   {To hold by the button}, to detain in conversation to
      weariness; to bore; to buttonhole.

Button \But"ton\, v. t. [imp. & p. p. {Buttoned}; p. pr. & vb.
   n. {Buttoning}.] [OE. botonen, OF. botoner, F. boutonner. See
   {Button}, n.]
   1. To fasten with a button or buttons; to inclose or make
      secure with buttons; -- often followed by up.

            He was a tall, fat, long-bodied man, buttoned up to
            the throat in a tight green coat.     --Dickens.

   2. To dress or clothe. [Obs.] --Shak.

Button \But"ton\, v. i.
   To be fastened by a button or buttons; as, the coat will not
   button.

Source : WordNet®

button
     n 1: a round fastener sewn to shirts and coats etc to fit through
          buttonholes
     2: an electrical switch operated by pressing a button; "the
        elevator was operated by push buttons"; "the push beside
        the bed operated a buzzer at the desk" [syn: {push button},
         {push}]
     3: any of various plant parts that resemble buttons
     4: a female sexual organ homologous to the penis [syn: {clitoris},
         {clit}]

button
     v 1: provide with buttons; "button a shirt"
     2: fasten with buttons; "button the dress" [ant: {unbutton}]

Source : Free On-Line Dictionary of Computing

button
     
        1.  {push-button}.
     
        2.  A graphical representation of an
        electrical {push-button} appearing as part of a {graphical
        user interface}.  Moving the {mouse pointer} over the
        graphical button and pressing one of the physical mouse
        buttons starts some software action such as closing a window
        or deleting a file.
     
        See also {radio button}.
     
        (1997-07-07)