The Collaborative International Dictionary of English v.0.48:

Motivate \Mo"ti*vate\, v. t. [imp. & p. p. -vated; p. pr. &
   vb. n. -vating.] [From Motive, n.]
   To provide with a motive; to move; impel; induce; incite. --
   Mo`ti*va"tion, n. --William James.

   Syn: move, prompt, incite, induce impel, drive.
        [Webster 1913 Suppl.]