The Collaborative International Dictionary of English v.0.48:

Conceptual \Con*cep"tu*al\, a.
   Pertaining to conception.
   [1913 Webster]

WordNet (r) 3.0 (2006):

conceptual
    adj 1: being or characterized by concepts or their formation;
           "conceptual discussions"; "the schizophrenic loses
           ability to abstract or do conceptual thinking"; "sex is a
           notional category, gender is a grammatical category"

Moby Thesaurus II by Grady Ward, 1.0:

81 Moby Thesaurus words for "conceptual":
   bright, cerebral, cogitative, cognitive, concentrating,
   concentrative, conceptive, conceptualized, contemplating,
   contemplative, creative, deliberating, deliberative, discursive,
   endopsychic, esemplastic, excogitating, fanciful, fecund, fertile,
   germinal, ideal, ideational, ideative, ideological, imaginative,
   ingenious, inspired, intellectual, intelligent, internal,
   introspective, inventive, knowing, meditating, meditative, mental,
   museful, musing, noetic, noological, not so dumb, notional,
   original, originative, pensive, phrenic, pondering, pregnant,
   prehensive, productive, prolific, psychic, psychologic, rational,
   reasonable, reasoning, reflecting, reflective, ruminant,
   ruminating, ruminative, sane, seminal, sensible, serious, shaping,
   sober, sophic, speculative, spiritual, strong-minded, subjective,
   teeming, theoretical, thinking, thought, thoughtful, understanding,
   visioned, wistful