The Collaborative International Dictionary of English v.0.48:

Complot \Com"plot\, n. [F. complot, prob. for comploit, fr.L.
   complicitum, prop. p. p. of complicare, but equiv. to
   complicatio complication, entangling. See Complicate, and
   cf. Plot.]
   A plotting together; a confederacy in some evil design; a
   conspiracy.
   [1913 Webster]

         I know their complot is to have my life. --Shak.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Complot \Com*plot"\, v. t. & i. [imp. & p. p. Complotted; p.
   pr. & vb. n. Complotting.] [Cf. F. comploter, fr. complot.]
   To plot or plan together; to conspire; to join in a secret
   design.
   [1913 Webster]

         We find them complotting together, and contriving a new
         scene of miseries to the Trojans.        --Pope.
   [1913 Webster]

WordNet (r) 3.0 (2006):

complot
    v 1: engage in plotting or enter into a conspiracy, swear
         together; "They conspired to overthrow the government"
         [syn: conspire, cabal, complot, conjure,
         machinate]