The Collaborative International Dictionary of English v.0.48:

Prostration \Pros*tra"tion\, n. [L. prostratio: cf. F.
   prostration.]
   1. The act of prostrating, throwing down, or laying fiat; as,
      the prostration of the body.
      [1913 Webster]

   2. The act of falling down, or of bowing in humility or
      adoration; primarily, the act of falling on the face, but
      usually applied to kneeling or bowing in reverence and
      worship.
      [1913 Webster]

            A greater prostration of reason than of body.
                                                  --Shak.
      [1913 Webster]

   3. The condition of being prostrate; great depression;
      lowness; dejection; as, a postration of spirits. "A sudden
      prostration of strength." --Arbuthnot.
      [1913 Webster]

   4. (Med.) A latent, not an exhausted, state of the vital
      energies; great oppression of natural strength and vigor.
      [1913 Webster]

   Note: Prostration, in its medical use, is analogous to the
         state of a spring lying under such a weight that it is
         incapable of action; while exhaustion is analogous to
         the state of a spring deprived of its elastic powers.
         The word, however, is often used to denote any great
         depression of the vital powers.
         [1913 Webster]

WordNet (r) 3.0 (2006):

prostration
    n 1: an abrupt failure of function or complete physical
         exhaustion; "the commander's prostration demoralized his
         men" [syn: collapse, prostration]
    2: abject submission; the emotional equivalent of prostrating
       your body
    3: the act of assuming a prostrate position

Moby Thesaurus II by Grady Ward, 1.0:

190 Moby Thesaurus words for "prostration":
   accubation, accumbency, aching heart, adoration, adulation,
   adynamia, agony, agony of mind, anemia, anguish, apple-polishing,
   ass-kissing, atony, backscratching, bale, bend, bending the knee,
   bitterness, blah feeling, bleeding heart, bloodlessness, bob,
   bootlicking, bouleversement, bow, bowing, bowing and scraping,
   breakdown, broken heart, brown-nosing, cachexia, cachexy, care,
   carking care, cave-in, circulatory collapse, co-worship, collapse,
   convulsion, couchancy, cowardice, crack-up, crackup, cringing,
   crouch, crushing, cult, cultism, cultus, curtsy, debasement,
   debilitation, debility, decumbency, deference, deflation,
   dejection, depression, depth of misery, desolation, despair,
   desperation, despondency, devotion, dipping the colors, downfall,
   draining, duck, dulia, dullness, enervation, etiolation,
   exhaustedness, exhaustion, extremity, faintness, fall, fatigue,
   fawnery, fawning, feebleness, flabbiness, flaccidity, flunkyism,
   footlicking, genuflection, grief, groveling, handshaking,
   heartache, heartfelt grief, heartgrief, heavy heart, homage,
   humiliation, hyperdulia, idolatry, implosion, impotence,
   inclination, infelicity, ingratiation, insinuation, kneeling,
   kowtow, kowtowing, lamentation, languishment, languor, lassitude,
   latria, listlessness, loll, lounging, lowness, lying, lying down,
   making a leg, mealymouthedness, melancholia, melancholy, misery,
   nervous breakdown, nervous exhaustion, nervous prostration,
   neurasthenia, nod, obeisance, obsequiousness, overthrow, overturn,
   paralysis, parasitism, pining, presenting arms, proneness,
   reclination, reclining, recumbency, repose, respect, reverence,
   sabotage, sadness, salaam, salutation, salute, scrape, servility,
   shortness, sluggishness, softness, sorrow, sorrowing, sponging,
   sprawl, squat, squatness, squattiness, standing at attention,
   stoop, strengthlessness, stumpiness, subjacency, submission,
   submissiveness, subversion, suicidal despair, supination,
   supineness, sycophancy, timeserving, toadeating, toadying,
   toadyism, transcendent wonder, truckling, tufthunting, unhappiness,
   upheaval, upset, veneration, weakliness, weakness, weariness, woe,
   woefulness, worship, worshiping, wretchedness