The Collaborative International Dictionary of English v.0.48:

Machinate \Mach"i*nate\, v. i. [imp. & p. p. Machinated; p.
   pr. & vb. n. Machinating.] [L. machinatus, p. p. of
   machinari to devise, plot. See Machine.]
   To plan; to contrive; esp., to form a scheme with the purpose
   of doing harm; to contrive artfully; to plot. "How long will
   you machinate!" --Sandys.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Machinate \Mach"i*nate\, v. t.
   To contrive, as a plot; to plot; as, to machinate evil.
   [1913 Webster]

WordNet (r) 3.0 (2006):

machinate
    v 1: arrange by systematic planning and united effort;
         "machinate a plot"; "organize a strike"; "devise a plan to
         take over the director's office" [syn: organize,
         organise, prepare, devise, get up, machinate]
    2: engage in plotting or enter into a conspiracy, swear
       together; "They conspired to overthrow the government" [syn:
       conspire, cabal, complot, conjure, machinate]

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "machinate":
   angle, brew, cabal, cogitate, collude, complot, concoct, connive,
   conspire, contrive, cook up, countermine, counterplot, devise,
   engineer, finagle, finesse, frame, frame up, gerrymander, hatch,
   hatch a plot, hatch up, intrigue, jockey, lay a plot, maneuver,
   manipulate, operate, play games, plot, pull strings, rig, scheme,
   wangle