The Collaborative International Dictionary of English v.0.48:

Desolate \Des"o*late\, v. t. [imp. & p. p. Desolated; p. pr. &
   vb. n. Desolating.]
   1. To make desolate; to leave alone; to deprive of
      inhabitants; as, the earth was nearly desolated by the
      flood.
      [1913 Webster]

   2. To lay waste; to ruin; to ravage; as, a fire desolates a
      city.
      [1913 Webster]

            Constructed in the very heart of a desolating war.
                                                  --Sparks.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Desolate \Des"o*late\, a. [L. desolatus, p. p. of desolare to
   leave alone, forsake; de- + solare to make lonely, solus
   alone. See Sole, a.]
   1. Destitute or deprived of inhabitants; deserted;
      uninhabited; hence, gloomy; as, a desolate isle; a
      desolate wilderness; a desolate house.
      [1913 Webster]

            I will make Jerusalem . . . a den of dragons, and I
            will make the cities of Judah desolate, without an
            inhabitant.                           --Jer. ix. 11.
      [1913 Webster]

            And the silvery marish flowers that throng
            The desolate creeks and pools among.  --Tennyson.
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   2. Laid waste; in a ruinous condition; neglected; destroyed;
      as, desolate altars.
      [1913 Webster]

   3. Left alone; forsaken; lonely; comfortless.
      [1913 Webster]

            Have mercy upon, for I am desolate.   --Ps. xxv. 16.
      [1913 Webster]

            Voice of the poor and desolate.       --Keble.
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   4. Lost to shame; dissolute. [Obs.] --Chaucer.
      [1913 Webster]

   5. Destitute of; lacking in. [Obs.]
      [1913 Webster]

            I were right now of tales desolate.   --Chaucer.

   Syn: Desert; uninhabited; lonely; waste.
        [1913 Webster]

WordNet (r) 3.0 (2006):

desolate
    adj 1: providing no shelter or sustenance; "bare rocky hills";
           "barren lands"; "the bleak treeless regions of the high
           Andes"; "the desolate surface of the moon"; "a stark
           landscape" [syn: bare, barren, bleak, desolate,
           stark]
    2: crushed by grief; "depressed and desolate of soul"; "a low
       desolate wail"
    v 1: leave someone who needs or counts on you; leave in the
         lurch; "The mother deserted her children" [syn: abandon,
         forsake, desolate, desert]
    2: reduce in population; "The epidemic depopulated the
       countryside" [syn: depopulate, desolate]
    3: cause extensive destruction or ruin utterly; "The enemy lay
       waste to the countryside after the invasion" [syn: lay waste
       to, waste, devastate, desolate, ravage, scourge]

Moby Thesaurus II by Grady Ward, 1.0:

200 Moby Thesaurus words for "desolate":
   abandoned, acarpous, acheronian, afflict, aggrieve, agonize, alone,
   anguish, annihilate, arid, bare, barren, black, bleak, break down,
   bring to ruin, bring to tears, celibate, cheerless, childless,
   comfortless, condemn, confound, consume, crush, crushed, cut up,
   damn, dark, daunt, deal destruction, decimate, deep-troubled,
   defenseless, deject, dejected, demolish, depopulate, depredate,
   depress, depressed, desecrate, desert, deserted, desole, despoil,
   despondent, destitute, destroy, destroyed, devastate, devastated,
   devour, disconsolate, discourage, discouraged, dishearten, dismal,
   dismay, dispeople, dispirit, dispirited, dissolve, distressed,
   down, downcast, downhearted, drained, draw tears, drear, dreary,
   dried-up, dry, embitter, empty, engorge, excruciate, exhausted,
   fallow, fatherless, forlorn, forsaken, friendless, fruitless,
   funereal, gaunt, gelded, gloomy, gobble, gobble up, godforsaken,
   grieve, gut, gut with fire, havoc, heart-stricken, heart-struck,
   heartsick, heartsore, helpless, homeless, hopeless, impotent,
   incinerate, inconsolable, ineffectual, infecund, infertile,
   inundate, isolated, issueless, jejune, joyless, kithless,
   lay in ruins, lay waste, leached, lonely, low-spirited, melancholy,
   menopausal, miserable, motherless, mournful, murky, neglected,
   nonfertile, nonproducing, nonproductive, nonprolific, obliterate,
   oppress, outcast, overwhelm, pillage, poor, poverty-stricken,
   prostrate, ravage, ravaged, raze, remote, ruin, ruinate, ruined,
   sack, sad, sadden, shipwreck, sick, sick at heart, sine prole,
   solitary, somber, sorrow, sorrowful, soul-sick, spiritless,
   spoliate, sterile, stricken, sucked dry, suicidal, swallow up,
   teemless, throw into disorder, torment, torture, unconsolable,
   uncouth, uncultivated, unfertile, unfrequented, unfriended,
   unfruitful, unhappy, uninhabited, unleash destruction,
   unleash the hurricane, unoccupied, unpeople, unplowed,
   unproductive, unprolific, unsown, untilled, upheave, vacant,
   vandalize, vaporize, virgin, waste, wasted, without issue,
   woebegone, woeful, wrack, wreak havoc, wreck, wretched