The Collaborative International Dictionary of English v.0.48:

Gyp \Gyp\ (j[i^]p), n. [Said to be a sportive application of Gr.
   gy`ps a vulture.]
   A college servant; -- so called in Cambridge, England; at
   Oxford called a scout. [Cant]
   [1913 Webster]

WordNet (r) 3.0 (2006):

gyp
    n 1: a swindle in which you cheat at gambling or persuade a
         person to buy worthless property [syn: bunco, bunco
         game, bunko, bunko game, con, confidence trick,
         confidence game, con game, gyp, hustle, sting,
         flimflam]
    v 1: deprive of by deceit; "He swindled me out of my
         inheritance"; "She defrauded the customers who trusted
         her"; "the cashier gypped me when he gave me too little
         change" [syn: victimize, swindle, rook, goldbrick,
         nobble, diddle, bunco, defraud, scam, mulct,
         gyp, gip, hornswoggle, short-change, con]

Moby Thesaurus II by Grady Ward, 1.0:

131 Moby Thesaurus words for "gyp":
   Partlet, Seeing Eye dog, ballot-box stuffing, bandog, beat,
   beguile of, biddy, bilk, bitch, bossy, bowwow, brood mare, bunco,
   burn, canine, cardsharping, cheat, cheating, chisel, chouse,
   chouse out of, cog, cog the dice, con, con man, cow, cozen,
   cozenage, crib, defraud, defrauder, diddle, diddler, diddling,
   dishonesty, do, do in, do out of, dodge, doe, dog, double-dealer,
   euchre, ewe, ewe lamb, fake, fancy dog, filly, finagle,
   fishy transaction, flam, fleece, flimflam, flimflammer, fob, fraud,
   fraudulence, fraudulency, fudge, gerrymandering, gouge, graft,
   grift, guide dog, guinea hen, gull, gyp joint, have, heifer, hen,
   hind, hoax, hocus, hocus-pocus, humbug, illicit business,
   imposition, imposture, jenny, kennel, lap dog, lioness, mare,
   mountebank, mulct, nanny, nanny goat, overreach, pack of dogs,
   pack the deal, peahen, phony, pigeon, pooch, practice fraud upon,
   pup, puppy, racket, roe, rook, scam, screw, sell, sell gold bricks,
   sharper, shave, she-bear, she-goat, she-lion, sheep dog,
   shortchange, show dog, sled dog, slut, sow, spoof, stack the cards,
   stick, sting, swindle, take a dive, thimblerig, throw a fight,
   tigress, toy dog, trickster, victimize, vixen, watchdog, whelp,
   working dog