WordNet (r) 3.0 (2006):

autodidactic
    adj 1: relating to or having the characteristics of an
           autodidact

Moby Thesaurus II by Grady Ward, 1.0:

39 Moby Thesaurus words for "autodidactic":
   bookish, coeducational, college-bred, collegiate, cultural,
   didactic, disciplinary, edifying, educated, educating, educational,
   educative, enlightening, exhortatory, graduate, homiletic,
   hortatory, illuminating, informative, initiatory, instructive,
   introductory, learned, lecturing, postgraduate, preaching,
   preceptive, propaedeutic, schoolboyish, schoolgirlish,
   self-educated, self-instructed, self-teaching, sophomoric,
   studentlike, studious, teaching, tuitionary, undergraduate