The Collaborative International Dictionary of English v.0.48:

Caparison \Ca*par"i*son\, v. t. [imp. & p. p. Caparisonedp.
   pr. & vb. n. Caparisoning.] [Cf. F capara[,c]onner.]
   [1913 Webster]
   1. To cover with housings, as a horse; to harness or fit out
      with decorative trappings, as a horse.
      [1913 Webster]

            The steeds, caparisoned with purple, stand.
                                                  --Dryden.
      [1913 Webster]

   2. To adorn with rich dress; to dress.
      [1913 Webster]

            I am caparisoned like a man.          --Shak.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Caparison \Ca*par"i*son\, n. [F. capara[,c]on, fr. Sp. caparazon
   a cover for a saddle, coach, etc.; capa cloak, cover (fr. LL.
   capa, cf. LL. caparo also fr. capa) + the term. azon. See
   Cap.]
   1. An ornamental covering or housing for a horse; the harness
      or trappings of a horse, taken collectively, especially
      when decorative.
      [1913 Webster]

            Their horses clothed with rich caparison. --Drylen.
      [1913 Webster]

   2. Gay or rich clothing.
      [1913 Webster]

            My heart groans beneath the gay caparison.
                                                  --Smollett.
      [1913 Webster]

WordNet (r) 3.0 (2006):

caparison
    n 1: stable gear consisting of a decorated covering for a horse,
         especially (formerly) for a warhorse [syn: caparison,
         trapping, housing]
    v 1: put a caparison on; "caparison the horses for the festive
         occasion" [syn: caparison, bard, barde, dress up]

Moby Thesaurus II by Grady Ward, 1.0:

62 Moby Thesaurus words for "caparison":
   accouterments, back band, backstrap, bearing rein, bellyband, bit,
   blinders, blinds, breeching, bridle, cavesson, checkrein,
   cheekpiece, chinband, cinch, collar, crownband, crupper, curb,
   furnishings, gag swivel, getup, girth, hackamore, halter, hames,
   hametugs, harness, headgear, headstall, hip straps, horse blanket,
   horsecloth, housing, jaquima, jerk line, lines, livery, martingale,
   noseband, outfit, pole strap, reins, ribbons, rig, saddle,
   saddle blanket, saddlecloth, shaft tug, side check, snaffle,
   surcingle, tack, tackle, things, trappings, trousseau, tug,
   turnout, wardrobe, winker braces, yoke