The Collaborative International Dictionary of English v.0.48:

Discompose \Dis`com*pose"\, v. t. [imp. & p. p. Discomposed;
   p. pr. & vb. n. Discomposing.] [Pref. dis- + compose: cf.
   OF. decomposer, F. d['e]composer.]
   1. To disarrange; to interfere with; to disturb; to disorder;
      to unsettle; to break up.
      [1913 Webster]

            Or discomposed the headdress of a prude. --Pope.
      [1913 Webster]

   2. To throw into disorder; to ruffle; to destroy the
      composure or equanimity; to agitate.
      [1913 Webster]

            Opposition . . . discomposeth the mind's serenity.
                                                  --Glanvill.
      [1913 Webster]

   3. To put out of place or service; to discharge; to displace.
      [Obs.] --Bacon.

   Syn: To disorder; derange; unsettle; disturb; disconcert;
        agitate; ruffle; fret; vex.
        [1913 Webster]

WordNet (r) 3.0 (2006):

discompose
    v 1: cause to lose one's composure [syn: upset, discompose,
         untune, disconcert, discomfit]

Moby Thesaurus II by Grady Ward, 1.0:

150 Moby Thesaurus words for "discompose":
   abash, addle, addle the wits, aggravate, agitate, annoy, badger,
   bait, ball up, be at, be tedious, beat, beat up, becloud, bedazzle,
   bedevil, befuddle, beset, bewilder, bore, bother, bristle,
   brown off, bug, bullyrag, burn up, cast down, chagrin, chivy,
   churn, churn up, cloud, confound, confuse, convulse, daze, dazzle,
   derange, devil, disagree, disarrange, disarray, discombobulate,
   discomfit, disconcert, discontent, dishevel, dismay, disorder,
   disorganize, disorient, disquiet, distemper, distract, disturb,
   dog, electrify, embarrass, embroil, entangle, exasperate, excite,
   exercise, fash, ferment, flummox, flurry, fluster, flutter, fog,
   fret, fuddle, fuss, get, gripe, harass, harry, heckle, hector,
   hound, irk, jar, jolt, jumble, knock galley-west,
   leave unsatisfied, maze, mess up, miff, mist, mix up, moider,
   molest, mortify, muddle, nag, needle, nettle, nudzh, paddle, peeve,
   perplex, persecute, perturb, perturbate, pester, pick on, pique,
   plague, pluck the beard, pother, provoke, psych, put out,
   raise hell, rattle, ride, rile, ripple, rock, roil, roughen,
   ruffle, rummage, rumple, shake, shake up, shock, spook, stagger,
   stir, stir up, swirl, tease, throw, throw into confusion, torment,
   trouble, try the patience, tweak the nose, unhinge, unsettle,
   untune, upset, vex, whip, whip up, whisk, work up, worry