The Collaborative International Dictionary of English v.0.48:

Introspect \In`tro*spect"\, v. t. [L. introspectus, p. p.
   introspicere to look into; intro within + specere to look.
   See Spy.]
   To look into or within; to view the inside of. --Bailey.
   [1913 Webster]

WordNet (r) 3.0 (2006):

introspect
    v 1: reflect on one's own thoughts and feelings

Moby Thesaurus II by Grady Ward, 1.0:

20 Moby Thesaurus words for "introspect":
   be abstracted, brood, chew the cud, consider, contemplate, debate,
   deliberate, digest, meditate, muse, perpend, play around with,
   play with, ponder, reflect, ruminate, speculate, study, toy with,
   weigh