1. [n]  a round fastener sewn to shirts and coats etc to fit through buttonholes
2. [n]  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"
3. [n]  a female sexual organ homologous to the penis
4. [n]  any of various plant parts that resemble buttons
5. [v]  fasten with buttons; "button the dress"
6. [v]  provide with buttons; "button a shirt"

1. \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.
   

2. \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.
   

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