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.

Source : WordNet®

button tree
     n : evergreen tree or shrub with fruit resembling buttons and
         yielding heavy hard compact wood [syn: {button mangrove},
          {Conocarpus erectus}]