Source : Webster's Revised Unabridged Dictionary (1913)

Cogitate \Cog"i*tate\, v. t.
   To think over; to plan.

         He . . . is our witness, how we both day and night,
         revolving in our minds, did cogitate nothing more than
         how to satisfy the parts of a good pastor. --Foxe.

Cogitate \Cog"i*tate\, v. i. [imp. & p. p. {Cogitated}; p. pr. &
   vb. n. {Cogitating}.] [L. cogitatus, p. p. of cogitare to
   reflect upon, prob. fr. co- + the root of aio I say; hence,
   prop., to discuss with one's self. Cf. {Adage}.]
   To engage in continuous thought; to think.

         He that calleth a thing into his mind, whether by
         impression or recordation, cogitateth and considereth,
         and he that employeth the faculty of his fancy also
         cogitateth.                              --Bacon.

Source : WordNet®

cogitate
     v 1: consider carefully and deeply; reflect upon; turn over in
          one's mind
     2: use or exercise the mind or one's power of reason in order
        to make inferences, decisions, or arrive at a solution or
        judgments; "I've been thinking all day and getting
        nowhere" [syn: {think}, {cerebrate}]