The Collaborative International Dictionary of English v.0.48:

Pooped \Pooped\, p. p. & a. (Naut.)
   (a) Having a poop; furnished with a poop.
   (b) Struck on the poop. [1913 Webster] pooped out

The Collaborative International Dictionary of English v.0.48:

Pooped \Pooped\, Pooped out \Pooped out\, a.
   Tired; exhausted; fatigued. [PJC]

The Collaborative International Dictionary of English v.0.48:

Poop \Poop\, v. i. [imp. & p. p. Pooped; p. pr. & vb. n.
   Pooping.] [Cf. D. poepen. See Pop.]
   To make a noise; to pop; also, to break wind.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

122 Moby Thesaurus words for "pooped":
   all in, anemic, apathetic, asthenic, ausgespielt, beat, beat up,
   beaten, benumbed, blase, bloodless, bone-weary, bored, bushed,
   chicken, cowardly, dead, dead-and-alive, dead-tired, deadbeat,
   debilitated, dog-tired, dog-weary, done, done in, done up, dopey,
   dormant, drained, drooping, droopy, drugged, dull, effete, emptied,
   enervated, etiolated, exanimate, exhausted, fagged out, faint,
   faintish, far-gone, fatigued, feeble, flabby, flaccid, floppy,
   frazzled, gone, gutless, heavy, hebetudinous, imbecile, impotent,
   inanimate, inert, jaded, knocked out, lackadaisical, laid low,
   languid, languorous, leaden, lethargic, lifeless, limber, limp,
   listless, lumpish, lustless, marrowless, moribund, nerveless, numb,
   phlegmatic, pithless, played out, pooped out, powerless, prostrate,
   ready to drop, rubbery, run-down, sapless, sated, shotten,
   sinewless, slack, sleepy, slow, sluggish, soft, somnolent, spent,
   spineless, stagnant, stagnating, strengthless, stultified, supine,
   tired, tired out, tired to death, torpid, tuckered out, unhardened,
   unnerved, unstrung, used up, vegetable, vegetative, wan, washed-up,
   weak, weakly, weary, weary unto death, whacked, wiped out,
   world-weary, worn-out