The Collaborative International Dictionary of English v.0.48:

Trifle \Tri"fle\, v. t.
   1. To make of no importance; to treat as a trifle. [Obs.]
      --Shak.
      [1913 Webster]

   2. To spend in vanity; to fritter away; to waste; as, to
      trifle away money. "We trifle time." --Shak.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Trifle \Tri"fle\, n. [OE. trifle, trufle, OF. trufle mockery,
   raillery, trifle, probably the same word as F. truffe
   truffle, the word being applied to any small or worthless
   object. See Truffle.]
   1. A thing of very little value or importance; a paltry, or
      trivial, affair.
      [1913 Webster]

            With such poor trifles playing.       --Drayton.
      [1913 Webster]

            Trifles light as air
            Are to the jealous confirmation strong
            As proofs of holy writ.               --Shak.
      [1913 Webster]

            Small sands the mountain, moments make year,
            And frifles life.                     --Young.
      [1913 Webster]

   2. A dish composed of sweetmeats, fruits, cake, wine, etc.,
      with syllabub poured over it.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Trifle \Tri"fle\, v. i. [imp. & p. p. Trifled; p. pr. & vb. n.
   Trifling.] [OE. trifelen, truflen. See Trifle, n.]
   To act or talk without seriousness, gravity, weight, or
   dignity; to act or talk with levity; to indulge in light or
   trivial amusements.
   [1913 Webster]

         They trifle, and they beat the air about nothing which
         toucheth us.                             --Hooker.
   [1913 Webster]

   To trifle with, to play the fool with; to treat without
      respect or seriousness; to mock; as, to trifle with one's
      feelings, or with sacred things.
      [1913 Webster]

WordNet (r) 3.0 (2006):

trifle
    n 1: a cold pudding made of layers of sponge cake spread with
         fruit or jelly; may be decorated with nuts, cream, or
         chocolate
    2: a detail that is considered insignificant [syn:
       technicality, trifle, triviality]
    3: something of small importance [syn: triviality, trivia,
       trifle, small beer]
    v 1: waste time; spend one's time idly or inefficiently [syn:
         piddle, wanton, wanton away, piddle away, trifle]
    2: act frivolously [syn: frivol, trifle]
    3: consider not very seriously; "He is trifling with her"; "She
       plays with the thought of moving to Tasmania" [syn: dally,
       trifle, play]

Moby Thesaurus II by Grady Ward, 1.0:

265 Moby Thesaurus words for "trifle":
   Charlotte, Danish pastry, French pastry, a continental, a curse,
   a damn, a darn, a hoot, abandon, bagatelle, baklava, bauble,
   be foolish, be stupid, bean, beguile the time, bibelot,
   bill and coo, bit, blintz, brass farthing, bric-a-brac,
   burn daylight, button, carrot pudding, cent, chaff, chicken feed,
   chickenshit, chocolate eclair, chocolate mousse, cipher, clown,
   clown around, consume time, copulate, coquet, cream puff, curio,
   custard, cut, dab, dabble, dally, dally away, dandle, dash,
   details, diddle, diddle away, doodle, dowdy, dribble away,
   drivel away, drop, dud, duff, dummy, eclair, farce, farthing,
   feather, fiddle, fiddle with, fiddle-faddle, fidget, fidget with,
   fig, finger with, flan, fleabite, flirt, flirt with, folderol,
   fool, fool around, fool away, fool with, footle, fribble, frippery,
   fritter away, fritter away time, frivol, froth, gaud, get funny,
   gewgaw, gimcrack, gimcrackery, go haywire, goldbrick, goof off,
   hair, halfpenny, hardly anything, hill of beans, hollow man,
   horse around, idle, idle away, invite ridicule, iota, jackstraw,
   jerk off, jest, joke, jot, jump, junket, kickshaw, kid around,
   kill time, knickknack, knickknackery, lay figure, lead on, leave,
   leave loose ends, leave undone, let alone, let be, let dangle,
   let go, little, loiter, lollygag, lose time, make love, make out,
   malinger, man of straw, mash, mere nothing, mess around, minikin,
   minutiae, miss, mite, mockery, molehill, monkey, monkey around,
   mousse, muck, mucker, muddle away, nebbish, neck, next to nothing,
   nobody, nonentity, nothing, novelty, nullity, omit, pandowdy,
   pass over, pass the time, pass up, pastry, pasty, patisserie,
   patty, patty-shell, peanuts, peppercorn, pet, philander, picayune,
   piddle, pie, pin, pinch, pinch of snuff, pinprick, piss away, play,
   play around, play the buffoon, play the fool, play with, plaything,
   plum pudding, potter, potter away, pretermit, procrastinate,
   pudding, puff, puppet, pushover, putter, quiche, rap, red cent,
   rennet, rosette, row of pins, rubbish, rush, scintilla, shade,
   shirk, shit, skip, slack, smack, small beer, small change, smatter,
   smidgen, smidgin, smooch, snap, sneeshing, sou, soupcon, spice,
   spoon, steamed pudding, straw, string along, strudel, suggestion,
   suspicion, sweet-talk, syllabub, tad, tapioca pudding, tart,
   thing of naught, timbale, tinker, tipsy cake, tittle, tomfool,
   touch, toy, toy with, trace, trash, trifle away, trifle with,
   trifles, trinket, trivia, triviality, trumpery, tuppence, turnover,
   twiddle, two cents, twopence, vanilla pudding, vol-au-vent, wanton,
   waste time, whatnot, whiff, while away, whim-wham,
   whisper sweet nothings, whit, zero