abstract, brood, cogent, cogitate, cognition, cognitive, concept, conceptual, conceptualize, contemplate, deja-vu, delusion, envisage, excogitate, figment, groupthink, hallucinate, haunt, hypothetical, impulse, indelible, indiscriminately, introspective, metacognition, mindless, mull, muse, notional, paradox, pensive, ponder, psychology, qualitative, recollect, retrospect, reverie, ruminate, stupor, subconscious, subjectivity, transitory