The Collaborative International Dictionary of English v.0.48:

Desolation \Des`o*la"tion\, n. [F. d['e]solation, L. desolatio.]
   1. The act of desolating or laying waste; destruction of
      inhabitants; depopulation.
      [1913 Webster]

            Unto the end of the war desolations are determined.
                                                  --Dan. ix. 26.
      [1913 Webster]

   2. The state of being desolated or laid waste; ruin;
      solitariness; destitution; gloominess.
      [1913 Webster]

            You would have sold your king to slaughter, . . .
            And his whole kingdom into desolation. --Shak.
      [1913 Webster]

   3. A place or country wasted and forsaken.
      [1913 Webster]

            How is Babylon become a desolation!   --Jer. l. 23.

   Syn: Waste; ruin; destruction; havoc; devastation; ravage;
        sadness; destitution; melancholy; gloom; gloominess.
        [1913 Webster]

WordNet (r) 3.0 (2006):

desolation
    n 1: the state of being decayed or destroyed [syn:
         devastation, desolation]
    2: a bleak and desolate atmosphere; "the nakedness of the
       landscape" [syn: bleakness, desolation, bareness,
       nakedness]
    3: sadness resulting from being forsaken or abandoned [syn:
       forlornness, loneliness, desolation]
    4: an event that results in total destruction [syn:
       devastation, desolation]

Moby Thesaurus II by Grady Ward, 1.0:

114 Moby Thesaurus words for "desolation":
   Arabia Deserta, Death Valley, Sahara, abandonment, aching heart,
   agonizingness, agony, agony of mind, anguish, bale, barren,
   barren land, barrenness, barrens, bitterness, bleeding heart,
   bloodbath, blue ruin, breakup, broken heart, brush, bush, carnage,
   chaos, comfortlessness, consumption, crushing, damnation,
   decimation, defenselessness, depopulation, depredation, depression,
   depth of misery, desert, desertion, desolateness, despair,
   despoilment, despoliation, destruction, devastation,
   disconsolateness, disconsolation, disintegration, disorganization,
   dispeoplement, disruption, dissolution, distress, dolor,
   dreariness, dust bowl, excruciatingness, excruciation, extirpation,
   extremity, fatherlessness, forlornness, gloom, grief, havoc,
   heartache, heartbreak, heartsickness, heath, heavy heart, hecatomb,
   helplessness, holocaust, homelessness, howling wilderness,
   inconsolability, infelicity, karroo, kithlessness, lunar landscape,
   lunar waste, melancholia, melancholy, misery, motherlessness,
   obliteration, prostration, ravage, ravagement, ruin, ruination,
   sack, sadness, salt flat, shambles, slaughter, sorrow, spoliation,
   suicidal despair, torment, tormentingness, torture, torturousness,
   undoing, unhappiness, vandalism, waste, wasteland, weary waste,
   wild, wilderness, wilds, woe, wrack, wrack and ruin, wreck,
   wretchedness