The Collaborative International Dictionary of English v.0.48:

Push button \Push button\ (Elec.)
   A simple device, resembling a button in form, so arranged
   that pushing it closes an electric circuit, as of an electric
   bell; -- called also button.
   [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

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.
      [1913 Webster]

   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.
      [1913 Webster]

   3. A bud; a germ of a plant. --Shak.
      [1913 Webster]

   4. A piece of wood or metal, usually flat and elongated,
      turning on a nail or screw, to fasten something, as a
      door.
      [1913 Webster]

   5. A globule of metal remaining on an assay cupel or in a
      crucible, after fusion.
      [1913 Webster]

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

   Button shell (Zool.), 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.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

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.
      [1913 Webster]

            He was a tall, fat, long-bodied man, buttoned up to
            the throat in a tight green coat.     --Dickens.
      [1913 Webster]

   2. To dress or clothe. [Obs.] --Shak.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Button \But"ton\, v. i.
   To be fastened by a button or buttons; as, the coat will not
   button.
   [1913 Webster]

WordNet (r) 3.0 (2006):

button
    n 1: a round fastener sewn to shirts and coats etc to fit
         through buttonholes
    2: an electrical switch operated by pressing; "the elevator was
       operated by push buttons"; "the push beside the bed operated
       a buzzer at the desk" [syn: push button, push, button]
    3: any of various plant parts that resemble buttons
    4: a round flat badge displaying information and suitable for
       pinning onto a garment; "they passed out campaign buttons for
       their candidate"
    5: a female sexual organ homologous to the penis [syn:
       clitoris, clit, button]
    6: a device that when pressed will release part of a mechanism
       [syn: release, button]
    7: any artifact that resembles a button
    v 1: provide with buttons; "button a shirt"
    2: fasten with buttons; "button the dress" [ant: unbutton]

Moby Thesaurus II by Grady Ward, 1.0:

359 Moby Thesaurus words for "button":
   a continental, a curse, a damn, a darn, a hoot, anchor, armory,
   articulate, badge, badge of office, badges, bagatelle, band,
   bandage, bang, bantam, banty, bar, barrette, barricade, baton,
   batten, batten down, bauble, bean, bellyband, belt, bibelot, bilge,
   bind, binding, binding stone, binding twine, bit, blain, blazonry,
   bleb, blister, blob, bobby pin, bollard, bolt, bonder, bondstone,
   boss, bow, box hook, brace, braces, brad, braid, brass farthing,
   brassard, bubble, buckle, bulb, bulge, bulla, bullion, bump, bunch,
   burl, butt, button up, cable, cahot, cap and gown, carpet tack,
   cast, casting, catch, cent, chain, chain of office, chin, chine,
   chit, choke, choke off, cinch, cincture, clamp, clap, clasp,
   class ring, cleat, click, clinch, clip, close, close up,
   clothespin, clump, cockade, collar, condyle, constrict, contain,
   contract, convex, corking pin, cotter, cover, cross, curio,
   decoration, diminutive, dovetail, dowel, dress, eagle, ear,
   emblems, ensigns, farce, farthing, fasces, fasten, feather,
   featherweight, fibula, fig, figurehead, fillet, fingerling,
   fishhook, flange, flap, fleabite, fleur-de-lis, fold, fold up,
   folderol, fribble, frippery, funiculus, gall, garter, gate, gaud,
   gewgaw, gimcrack, girdle, girth, gnarl, grab, grapnel, grappler,
   grappling iron, guy, hair, hairpin, halfpenny, hammer and sickle,
   handle, hank, hasp, hawser, haywire, heraldry, hill, hill of beans,
   hinge, hitch, hitching post, holdfast, hook, hook and eye, hump,
   hunch, ingot, inkle, insignia, interlocker, jam, jest, jog, joggle,
   joint, joke, kevel, key, kickshaw, kingpin, knickknack,
   knickknackery, knob, knot, knur, knurl, lace, lacing, lapel pin,
   lariat, latch, latchet, leader, ligament, lightweight, line, lip,
   livery, lock, lock out, lock up, loop, lump, mace, mantle,
   markings, medal, mentum, mini, minikin, minnow, minny, miter,
   mockery, mole, molehill, moorings, mortarboard, mortise, mountain,
   mouse, nail, nevus, noose, nub, nubbin, nubble, nut, occlude,
   old school tie, padlock, paper clip, papilloma, pawl, peewee, peg,
   peppercorn, picayune, pig, pin, pinch of snuff, pinprick, pintle,
   plumb, pony, rabbet, rap, red cent, regalia, regulus, rib, ridge,
   ring, rivet, roller, rope, rose, row of pins, runt, rush,
   safety pin, scarf, school ring, screw, seal, seal off, seal up,
   secure, sennit, setscrew, sew, shamrock, sheet metal, shit,
   shoulder, shrimp, shut, shut the door, shut up, sigillography,
   skewer, skull and crossbones, slam, slide fastener, slip,
   small fry, snap, sneeshing, snip, snippet, snubbing post, sou, sow,
   sphragistics, spike, spine, splice, squeeze shut, staff, staple,
   stick, stitch, strangle, strap, straw, string, strop, stub tenon,
   stud, style, suspenders, swastika, tab, tack, tag, tartan, tendon,
   terret, thistle, thole, tholepin, thong, thumbtack, tie, tie beam,
   tit, toggle, toy, treenail, trifle, trinket, triviality, tubercle,
   tubercule, tug, tuppence, twine, two cents, twopence, uniform,
   verge, verruca, vesicle, vise, wale, wand, wart, wedge, welt,
   whang, whim-wham, wire, wisp, zip up, zipper



The Free On-line Dictionary of Computing (30 December 2018):

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)