The Collaborative International Dictionary of English v.0.48:

Stratagem \Strat"a*gem\, n. [F. stratag[`e]me (cf. Sp.
   estratagema, It. stratagemma), L. strategema, Gr. ?, fr. ? to
   be leader of an army, fr. ? a general; ? an army (probably as
   being spread out; cf. Stratum) + ? to lead. See Agent.]
   An artifice or trick in war for deceiving the enemy; hence,
   in general, artifice; deceptive device; secret plot; evil
   machination.
   [1913 Webster]

         Fit for treasons, stratagems, and spoils. --Shak.
   [1913 Webster]

         Those oft are stratagems which error seem,
         Nor is it Homer nods, but we that dream. --Pope.
   [1913 Webster]

WordNet (r) 3.0 (2006):

stratagem
    n 1: a maneuver in a game or conversation [syn: ploy,
         gambit, stratagem]
    2: an elaborate or deceitful scheme contrived to deceive or
       evade; "his testimony was just a contrivance to throw us off
       the track" [syn: contrivance, stratagem, dodge]

Moby Thesaurus II by Grady Ward, 1.0:

151 Moby Thesaurus words for "stratagem":
   action, ad hoc measure, alibi, answer, apology, art, artful dodge,
   artifice, bag of tricks, blind, bluff, bosey, cabal, catch,
   chicanery, chouse, cloak, collusion, color, complicity, complot,
   confederacy, connivance, conspiracy, contrivance, contriving,
   countermove, counterplot, coup, course of action, cover,
   cover story, cover-up, covin, craft, curve, curve-ball, cute trick,
   deceit, deep-laid plot, demarche, design, device, dirty deal,
   dirty trick, dodge, effort, engineering, excuse, expedient, facade,
   fakement, fast deal, feint, fetch, ficelle, finagling, finesse,
   frame-up, front, gambit, game, gimmick, gloss, googly, grift,
   guise, handle, hocus-pocus, improvisation, intrigue, joker, juggle,
   jugglery, jury-rig, jury-rigged expedient, knavery, lame excuse,
   last expedient, last resort, last shift, little game, locus standi,
   lure, machination, makeshift, maneuver, maneuvering, manipulation,
   mask, means, measure, move, ostensible motive, pass, pis aller,
   plan, play, plot, plotting, ploy, poor excuse, pretense,
   pretension, pretext, protestation, public motive, put-off, racket,
   red herring, refuge, resort, resource, rigging, ruse, scheme,
   schemery, scheming, screen, scurvy trick, semblance, shake-up,
   sham, shift, show, sleight, sleight of hand, sleight-of-hand trick,
   smoke screen, solution, stalking-horse, step, stopgap, strategy,
   stroke, stroke of policy, subterfuge, tactic, temporary expedient,
   trick, trickery, trump, underplot, varnish, veil, web of intrigue,
   wile, wily device, wire-pulling, working hypothesis,
   working proposition



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

STRATAGEM. A deception either by words or actions, in times of war, in order
to obtain an advantage over an enemy.
     2. Such stratagems, though contrary to morality, have been justified,
unless they have been accompanied by perfidy, injurious to the rights of
humanity, as in the example given by Vattel of an English frigate, which
during a war between France and England, appeared off Calais and made
signals of distress in order to allure some vessel to come to its relief,
and seized a shallop and its crew, who had generously gone out to render it
assistance. Vattel, Droit des Gens, liv. 3, c. 9, Sec. 178.
     3. Sometimes stratagems are employed in making, contracts, this is
unlawful and fraudulent, and avoids the contract. See Fraud.