The Collaborative International Dictionary of English v.0.48:

Gambit \Gam"bit\, n. [F. gambit, cf. It. gambitto gambit, a
   tripping up. See Gambol, n.] (Chess Playing)
   A mode of opening the game, in which a pawn is sacrificed to
   gain an attacking position.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

111 Moby Thesaurus words for "gambit":
   alpha, approach, art, artful dodge, artifice, assay, attempt,
   bag of tricks, bid, blind, bluff, bosey, breaking-in, catch,
   chicanery, chouse, conspiracy, contrivance, coup, crack, craft,
   curve, curve-ball, cute trick, deceit, design, device, dirty deal,
   dirty trick, dodge, effort, endeavor, essay, expedient, experiment,
   fakement, fast deal, feint, fetch, ficelle, first, first blush,
   first glance, first impression, first inning, first lap,
   first move, first round, first sight, first stage, first step,
   fling, game, gimmick, go, googly, grift, hocus-pocus, initial,
   initiative, intrigue, jig, joker, juggle, jugglery, knavery,
   le premier pas, lick, little game, maneuver, move, offer,
   opening move, pass, plan, play, plot, ploy, prime, primitiveness,
   primitivity, racket, red herring, ruse, scheme, scurvy trick,
   shift, shot, sleight, sleight of hand, sleight-of-hand trick, stab,
   step, stratagem, strategy, stroke, strong bid, subterfuge, tactic,
   tentative, trial, trial and error, trick, trickery, try,
   undertaking, warming-up, whack, whizzer, wile, wily device