The Collaborative International Dictionary of English v.0.48:

Trifling \Tri"fling\, a.
   Being of small value or importance; trivial; paltry; as, a
   trifling debt; a trifling affair. -- Tri"fling*ly, adv. --
   Tri"fling*ness, n.
   [1913 Webster] Trifloral

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):

trifling
    adj 1: not worth considering; "he considered the prize too
           paltry for the lives it must cost"; "piffling efforts";
           "a trifling matter" [syn: negligible, paltry,
           trifling]
    n 1: the deliberate act of delaying and playing instead of
         working [syn: dalliance, dawdling, trifling]

Moby Thesaurus II by Grady Ward, 1.0:

142 Moby Thesaurus words for "trifling":
   Mickey Mouse, airy, asinine, banal, bickering, brimful, brimming,
   captious, catchpenny, caviling, chic, chipper, chitchat,
   chitter-chatter, choplogic, classy, commonplace, coquetry, crammed,
   crowded, cursory, dabbling, dalliance, dallying, dashing, dawdling,
   depthless, dillydallying, dolce far niente, empty, equivocatory,
   evasive, fashionable, fatuous, few, fiddling, flimsy, flirtation,
   fooling, fooling around, foolish, footling, fribble, fribbling,
   frivolous, frothy, futile, goofing off, hairsplitting, hedging,
   hollow, idle, idling, inane, incidental, inconsequential,
   inconsiderable, insignificant, insipid, jammed, jejune,
   jerking off, kidding around, lazing, light, lingering, little,
   loaded, loafing, logic-chopping, loitering, lolling, lounging, low,
   meager, measly, messing around, miniature, minor, modish,
   monkeying, monkeying around, mopery, neat, negligible, niggling,
   nit-picking, no great shakes, nugacious, nugatory, orderly, otiose,
   packed, paltering, paltry, petty, picayune, picayunish, piddling,
   playing, playing around, pottering, puny, pussyfooting, puttering,
   quibbling, shallow, sharp, shipshape, short, shuffling, silly,
   skin-deep, slender, slight, small, smart, smattering, snappy, snug,
   spick-and-span, superficial, swank, tarrying, tidy, tinkering,
   tiny, toying, trichoschistic, trig, trim, trite, trivial,
   uncluttered, unimportant, vacuous, vain, valueless, vapid,
   well-groomed, windy, worthless