late 15c., machinacion, "a plotting, an intrigue," from Old French machinacion "plot, conspiracy, scheming, intrigue" and directly from Latin machinationem (nominative machinatio) "device, contrivance, machination," noun of action from past-participle stem of machinari "to contrive skillfully, to design; to scheme, to plot," from machina "machine, engine; device trick" (see machine (n.)). Related: Machinations.
c. 1600, "to lay plots, intrigue," a back-formation from machination, or else from Latin machinatus, past participle of machinari "to contrive skillfully; to design, scheme, plot." Transitive sense of "to plan, contrive, form (a plot, scheme, etc.)" also is from c. 1600. Related: Machinated; machinating; machinator.