The Collaborative International Dictionary of English v.0.48:

Machination \Mach`i*na"tion\, n. [L. machinatio: cf. F.
   machination.]
   1. The act of machinating. --Shak.
      [1913 Webster]

   2. That which is devised; a device; a hostile or treacherous
      scheme; an artful design or plot.
      [1913 Webster]

            Devilish machinations come to naught. --Milton.
      [1913 Webster]

            His ingenious machinations had failed. --Macaulay.
      [1913 Webster]

WordNet (r) 3.0 (2006):

machination
    n 1: a crafty and involved plot to achieve your (usually
         sinister) ends [syn: intrigue, machination]

Moby Thesaurus II by Grady Ward, 1.0:

64 Moby Thesaurus words for "machination":
   artifice, behind-the-scenes influence, cabal, chicane, chicanery,
   collusion, complicity, complot, confederacy, connivance, connivery,
   conspiracy, contrivance, contriving, counterplot, covin,
   deep-laid plot, design, designing, devices, dodgery, engineering,
   expedients, finagling, finesse, foul play, frame-up, gambit, game,
   influence, intrigue, intriguing, little game, maneuvering,
   maneuvers, manipulating, manipulation, move, pettifoggery,
   pettifogging, plot, plotting, ploy, political influence, practice,
   rigging, ruse, scheme, schemery, scheming, sharp practice,
   skulduggery, sleight, stratagem, supercherie, tactical maneuvers,
   tactics, trick, trickery, underhand dealing, underplot,
   web of intrigue, wile, wire-pulling



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

MACHINATION. The act by which some plot or conspiracy is set on foot.



The Devil's Dictionary (1881-1906):

MACHINATION, n.  The method employed by one's opponents in baffling
one's open and honorable efforts to do the right thing.

    So plain the advantages of machination
    It constitutes a moral obligation,
    And honest wolves who think upon't with loathing
    Feel bound to don the sheep's deceptive clothing.
    So prospers still the diplomatic art,
    And Satan bows, with hand upon his heart.
                                                                R.S.K.