The Collaborative International Dictionary of English v.0.48:

Intrigue \In*trigue"\ ([i^]n*tr[=e]g"), v. i. [imp. & p. p.
   Intrigued (-tr[=e]gd"); p. pr. & vb. n. Intriguing.] [F.
   intriguer, OF. intriquer, entriquer; cf. It. intrigare. See
   Intricate, Extricate.]
   1. To form a plot or scheme; to contrive to accomplish a
      purpose by secret artifice.
      [1913 Webster]

   2. To carry on a secret and illicit love or amour.
      [1913 Webster]