The Collaborative International Dictionary of English v.0.48:

Desperate \Des"per*ate\, n.
   One desperate or hopeless. [Obs.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Desperate \Des"per*ate\, a. [L. desperatus, p. p. of desperare.
   See Despair, and cf. Desperado.]
   1. Without hope; given to despair; hopeless. [Obs.]
      [1913 Webster]

            I am desperate of obtaining her.      --Shak.
      [1913 Webster]

   2. Beyond hope; causing despair; extremely perilous;
      irretrievable; past cure, or, at least, extremely
      dangerous; as, a desperate disease; desperate fortune.
      [1913 Webster]

   3. Proceeding from, or suggested by, despair; without regard
      to danger or safety; reckless; furious; as, a desperate
      effort. "Desperate expedients." --Macaulay.
      [1913 Webster]

   4. Extreme, in a bad sense; outrageous; -- used to mark the
      extreme predominance of a bad quality.
      [1913 Webster]

            A desperate offendress against nature. --Shak.
      [1913 Webster]

            The most desperate of reprobates.     --Macaulay.

   Syn: Hopeless; despairing; desponding; rash; headlong;
        precipitate; irretrievable; irrecoverable; forlorn; mad;
        furious; frantic.
        [1913 Webster]

WordNet (r) 3.0 (2006):

desperate
    adj 1: arising from or marked by despair or loss of hope; "a
           despairing view of the world situation"; "the last
           despairing plea of the condemned criminal"; "a desperate
           cry for help"; "helpless and desperate--as if at the end
           of his tether"; "her desperate screams" [syn:
           despairing, desperate]
    2: desperately determined; "do-or-die revolutionaries"; "a do-
       or-die conflict" [syn: desperate, do-or-die(a)]
    3: (of persons) dangerously reckless or violent as from urgency
       or despair; "a desperate criminal"; "taken hostage of
       desperate men"
    4: showing extreme courage; especially of actions courageously
       undertaken in desperation as a last resort; "made a last
       desperate attempt to reach the climber"; "the desperate
       gallantry of our naval task forces marked the turning point
       in the Pacific war"- G.C.Marshall; "they took heroic measures
       to save his life" [syn: desperate, heroic]
    5: showing extreme urgency or intensity especially because of
       great need or desire; "felt a desperate urge to confess"; "a
       desperate need for recognition"
    6: fraught with extreme danger; nearly hopeless; "a desperate
       illness"; "on all fronts the Allies were in a desperate
       situation due to lack of materiel"- G.C.Marshall; "a dire
       emergency" [syn: desperate, dire]
    n 1: a person who is frightened and in need of help; "they prey
         on the hopes of the desperate"

Moby Thesaurus II by Grady Ward, 1.0:

111 Moby Thesaurus words for "desperate":
   Dionysiac, accident-prone, aching for, acute, affording no hope,
   amok, apathetic, atrocious, bacchic, baffled, balked, berserk,
   bleak, breakneck, careless, cheerless, climacteric, comfortless,
   compelling, concentrated, corybantic, craving, critical, crucial,
   crying, dangerous, desirous of, despairing, despondent, desponding,
   devil-may-care, dire, disconsolate, dismal, exquisite, fierce,
   foiled, foolhardy, forlorn, frantic, frenetic, frenzied,
   frustrated, furious, grave, great, grim, hard pressed, hard up,
   harum-scarum, hasty, hazardous, headlong, heinous, hopeless,
   hotheaded, hurried, impetuous, in despair, in desperate straits,
   in extremis, in extremities, like one possessed, mad, madding,
   maenadic, maniac, maniacal, monstrous, overeager, overenthusiastic,
   overzealous, panic-stricken, perilous, pinched, precarious,
   precipitant, precipitate, precipitous, pressing, rabid, raging,
   ranting, rash, raving, raving mad, reckless, running wild,
   scandalous, serious, shocking, slap-bang, slapdash, sorely pressed,
   stark-raving mad, straitened, tenuous, terrible, thwarted,
   uncontrollable, unhopeful, up against it, urgent, vehement,
   venturesome, vicious, violent, wanton, wild, without hope,
   wretched



Bouvier's Law Dictionary, Revised 6th Ed (1856):

DESPERATE. Of which there is no hope.
     2. This term is used frequently, in making an inventory of a decedent's
effects, when a debt is considered so bad that there is no hope of
recovering it. It is then called a desperate debt, and, if it be so
returned, it will be prima facie, considered as desperate. See Toll. Ex. 248
2 Williams, Ex. 644; 1 Chit. Pr. 580. See Sperate.