The Collaborative International Dictionary of English v.0.48:

Spent \Spent\ (sp[e^]nt), a.
   1. Exhausted; worn out; having lost energy or motive force.
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            Now thou seest me
            Spent, overpowered, despairing of success.
                                                  --Addison.
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            Heaps of spent arrows fall and strew the ground.
                                                  --Dryden.
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   2. (Zool.) Exhausted of spawn or sperm; -- said especially of
      fishes.
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   Spent ball, a ball shot from a firearm, which reaches an
      object without having sufficient force to penetrate it.
      [1913 Webster] Sper

The Collaborative International Dictionary of English v.0.48:

Spend \Spend\, v. t. [imp. & p. p. Spent; p. pr. & vb. n.
   Spending.] [AS. spendan (in comp.), fr. L. expendere or
   dispendere to weigh out, to expend, dispense. See Pendant,
   and cf. Dispend, Expend, Spence, Spencer.]
   1. To weigh or lay out; to dispose of; to part with; as, to
      spend money for clothing.
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            Spend thou that in the town.          --Shak.
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            Wherefore do ye spend money for that which is not
            bread?                                --Isa. lv. 2.
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   2. To bestow; to employ; -- often with on or upon.
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            I . . . am never loath
            To spend my judgment.                 --Herbert.
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   3. To consume; to waste; to squander; to exhaust; as, to
      spend an estate in gaming or other vices.
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   4. To pass, as time; to suffer to pass away; as, to spend a
      day idly; to spend winter abroad.
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            We spend our years as a tale that is told. --Ps. xc.
                                                  9.
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   5. To exhaust of force or strength; to waste; to wear away;
      as, the violence of the waves was spent.
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            Their bodies spent with long labor and thirst.
                                                  --Knolles.
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WordNet (r) 3.0 (2006):

spent
    adj 1: depleted of energy, force, or strength; "impossible to
           grow tobacco on the exhausted soil"; "the exhausted food
           sources"; "exhausted oil wells" [syn: exhausted,
           spent] [ant: unexhausted]
    2: drained of energy or effectiveness; extremely tired;
       completely exhausted; "the day's shopping left her
       exhausted"; "he went to bed dog-tired"; "was fagged and
       sweaty"; "the trembling of his played out limbs"; "felt
       completely washed-out"; "only worn-out horses and cattle";
       "you look worn out" [syn: exhausted, dog-tired, fagged,
       fatigued, played out, spent, washed-out, worn-
       out(a), worn out(p)]

Moby Thesaurus II by Grady Ward, 1.0:

94 Moby Thesaurus words for "spent":
   ablated, acquitted, all in, ausgespielt, beat, beat up, beaten,
   bleary, bone-weary, burned-out, burnt up, bushed, consumed, dead,
   dead-and-alive, dead-tired, deadbeat, depleted, devitalized,
   disabled, discharged, dissipated, dog-tired, dog-weary, done,
   done for, done in, done up, down the drain, drained, eaten up,
   effete, emptied, enervated, enfeebled, eroded, eviscerated,
   exhausted, expended, fagged out, far-gone, fatigued, fini,
   finished, frazzled, gone, gone to waste, hired, impoverished,
   incapacitated, jaded, knocked out, laid low, liquidated, lost,
   misspent, paid, paid in full, played out, pooped, pooped out,
   postpaid, prepaid, prostrate, ready to drop, receipted, remitted,
   run to seed, run-down, salaried, sapped, settled, shotten,
   squandered, tired, tired out, tired to death, tuckered out, used,
   used up, waged, washed-out, washed-up, wasted, weakened, wearied,
   weary, weary unto death, whacked, wiped out, worn, worn away,
   worn out, worn-out