The Collaborative International Dictionary of English v.0.48:

Trim \Trim\, v. t. [imp. & p. p. Trimmed; p. pr. & vb. n.
   Trimming.] [OE. trimen, trumen, AS. trymian, trymman, to
   prepare, dispose, make strong, fr. trum firm, strong; of
   uncertain origin.]
   1. To make trim; to put in due order for any purpose; to make
      right, neat, or pleasing; to adjust.
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            The hermit trimmed his little fire.   --Goldsmith.
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   2. To dress; to decorate; to adorn; to invest; to embellish;
      as, to trim a hat.
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            A rotten building newly trimmed over. --Milton.
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            I was trimmed in Julia's gown.        --Shak.
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   3. To make ready or right by cutting or shortening; to clip
      or lop; to curtail; as, to trim the hair; to trim a tree.
      " And trimmed the cheerful lamp." --Byron.
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   4. (Carp.) To dress, as timber; to make smooth.
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   5. (Naut.)
      (a) To adjust, as a ship, by arranging the cargo, or
          disposing the weight of persons or goods, so equally
          on each side of the center and at each end, that she
          shall sit well on the water and sail well; as, to trim
          a ship, or a boat.
      (b) To arrange in due order for sailing; as, to trim the
          sails.
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   6. To rebuke; to reprove; also, to beat. [Colloq.]
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   To trim in (Carp.), to fit, as a piece of timber, into
      other work.

   To trim up, to dress; to put in order.
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            I found her trimming up the diadem
            On her dead mistress.                 --Shak.
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The Collaborative International Dictionary of English v.0.48:

Trimming \Trim"ming\,
   a. from Trim, v.
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         The Whigs are, essentially, an inefficient, trimming,
         halfway sort of a party.                 --Jeffrey.
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   Trimming joist (Arch.), a joist into which timber trimmers
      are framed; a header. See Header. --Knight.
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The Collaborative International Dictionary of English v.0.48:

Trimming \Trim"ming\, n.
   1. The act of one who trims.
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   2. That which serves to trim, make right or fitting, adjust,
      ornament, or the like; especially, the necessary or the
      ornamental appendages, as of a garment; hence, sometimes,
      the concomitants of a dish; a relish; -- usually in the
      plural.
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   3. The act of reprimanding or chastisting; as, to give a boy
      a trimming. [Colloq.]
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WordNet (r) 3.0 (2006):

trimming
    n 1: the act of adding decoration; "the children had to be in
         bed before it was time for the trimming of the tree"
    2: a decoration or adornment on a garment; "the trimming on a
       hat"; "the trim on a shirt" [syn: trimming, trim,
       passementerie]
    3: cutting down to the desired size or shape [syn: trim,
       trimming, clipping]

Moby Thesaurus II by Grady Ward, 1.0:

142 Moby Thesaurus words for "trimming":
   Smyth sewing, Waterloo, adjunct, adornment, arrangement, backing,
   beading, beating, bibliopegy, binder board, binding, bonus,
   book cloth, book cover, book jacket, bookbinding, bookcase,
   bordering, bordure, case, casemaking, casing-in, collapse,
   collating, collating mark, color, color patterns, conquering,
   conquest, cover, crash, deathblow, debacle, decor, decoration,
   defeat, destruction, downfall, drubbing, dust cover, dust jacket,
   edging, elaboration, embellishment, emblazonment, emblazonry,
   embroidery, extra, extra added attraction, extra dash, failure,
   fall, filigree, filling, fillip, fimbria, fimbriation, flounce,
   flourish, flower arrangement, folding, footband, frill, frilling,
   fringe, furbelow, furniture arrangement, galloon, garnish,
   garnishment, garniture, gathering, gluing-off, hard binding,
   headband, hem, hiding, illumination, jacket, lagniappe, lambasting,
   lathering, library binding, licking, lining, lining-up, list,
   mastery, mechanical binding, motif, niggerhead, ornament,
   ornamentation, overcoming, overthrow, overturn, padding,
   perfect binding, plastic binding, premium, quietus, rounding,
   ruffle, ruin, saddle stitching, selvage, sewing, side sewing,
   signature, skirting, slipcase, slipcover, smash, smashing,
   soft binding, something extra, spiral binding, stamping, stapling,
   stuffing, subdual, subduing, subjugation, superaddition, supple,
   tailband, temporizing, thrashing, timeserving, tipping, trim,
   trouncing, twist, undoing, valance, vanquishment, welt, whipping,
   window dressing, wire stitching, wrapper, wrinkle