The Collaborative International Dictionary of English v.0.48:

Plume \Plume\, n. [F., fr. L. pluma. Cf. Fly, v.]
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   1. A feather; esp., a soft, downy feather, or a long,
      conspicuous, or handsome feather.
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            Wings . . . of many a colored plume.  --Milton.
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   2. (Zool.) An ornamental tuft of feathers.
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   3. A feather, or group of feathers, worn as an ornament; a
      waving ornament of hair, or other material resembling
      feathers.
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            His high plume, that nodded o'er his head. --Dryden.
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   4. A token of honor or prowess; that on which one prides
      himself; a prize or reward. "Ambitious to win from me some
      plume." --Milton.
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   5. (Bot.) A large and flexible panicle of inflorescence
      resembling a feather, such as is seen in certain large
      ornamental grasses.
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   Plume bird (Zool.), any bird that yields ornamental plumes,
      especially the species of Epimarchus from New Guinea, and
      some of the herons and egrets, as the white heron of
      Florida (Ardea candidissima).

   Plume grass. (Bot)
      (a) A kind of grass (Erianthus saccharoides) with the
          spikelets arranged in great silky plumes, growing in
          swamps in the Southern United States.
      (b) The still finer Erianthus Ravenn[ae] from the
          Mediterranean region. The name is sometimes extended
          to the whole genus.

   Plume moth (Zool.), any one of numerous small, slender
      moths, belonging to the family Pterophorid[ae]. Most of
      them have the wings deeply divided into two or more
      plumelike lobes. Some species are injurious to the
      grapevine.

   Plume nutmeg (Bot.), an aromatic Australian tree
      (Atherosperma moschata), whose numerous carpels are
      tipped with long plumose persistent styles.
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The Collaborative International Dictionary of English v.0.48:

Plume \Plume\, v. t. [imp. & p. p. Plumed; p. pr. & vb. n.
   Pluming.] [Cf. F. plumer to pluck, to strip, L. plumare to
   cover with feathers.]
   1. To pick and adjust the plumes or feathers of; to dress or
      prink.
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            Pluming her wings among the breezy bowers. --W.
                                                  Irving.
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   2. To strip of feathers; to pluck; to strip; to pillage;
      also, to peel. [Obs.] --Bacon. Dryden.
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   3. To adorn with feathers or plumes. "Farewell the plumed
      troop." --Shak.
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   4. To pride; to vaunt; to boast; -- used reflexively; as, he
      plumes himself on his skill. --South.
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   Plumed adder (Zool.), an African viper (Vipera cornuta,
      syn. Clotho cornuta), having a plumelike structure over
      each eye. It is venomous, and is related to the African
      puff adder. Called also horned viper and hornsman.

   Plumed partridge (Zool.), the California mountain quail
      (Oreortyx pictus). See Mountain quail, under
      Mountain.
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WordNet (r) 3.0 (2006):

plume
    n 1: anything that resembles a feather in shape or lightness; "a
         plume of smoke"; "grass with large plumes"
    2: a feather or cluster of feathers worn as an ornament
    3: the light horny waterproof structure forming the external
       covering of birds [syn: feather, plume, plumage]
    v 1: rip off; ask an unreasonable price [syn: overcharge,
         soak, surcharge, gazump, fleece, plume, pluck,
         rob, hook] [ant: undercharge]
    2: be proud of; "He prides himself on making it into law school"
       [syn: pride, plume, congratulate]
    3: deck with a plume; "a plumed helmet"
    4: clean with one's bill; "The birds preened" [syn: preen,
       plume]
    5: form a plume; "The chimneys were pluming the sky"; "The
       engine was pluming black smoke"
    6: dress or groom with elaborate care; "She likes to dress when
       going to the opera" [syn: preen, primp, plume, dress]

Moby Thesaurus II by Grady Ward, 1.0:

37 Moby Thesaurus words for "plume":
   bead, bejewel, beribbon, bespangle, brush up, crest, diamond,
   dress, engrave, feather, fettle, figure, filigree, flag, flounce,
   flower, garland, gem, groom, hackle, illuminate, jewel, manicure,
   paint, panache, pinion, pique, plumule, preen, quill, ribbon,
   scapular, spangle, tinsel, topknot, tuft, wreathe