WordNet (r) 3.0 (2006):

superego
    n 1: (psychoanalysis) that part of the unconscious mind that
         acts as a conscience

Moby Thesaurus II by Grady Ward, 1.0:

73 Moby Thesaurus words for "superego":
   I, I myself, alter, alter ego, alterum, anima, better self, censor,
   coconscious, collective unconscious, conscience, conscientiousness,
   conscious self, death instinct, ego, ego ideal, ego-id conflict,
   ethical self, foreconscious, grace, he, her, herself, him, himself,
   id, inner arbiter, inner man, inner self, inward monitor, it,
   libidinal energy, libido, me, mind, moral censor, motive force,
   my humble self, myself, number one, oneself, other self, ourselves,
   persona, personality, pleasure principle, preconscious,
   primitive self, psyche, psychic apparatus, racial unconscious,
   self, she, social conscience, subconscious, subconscious mind,
   subconscious self, subliminal, subliminal self, submerged mind,
   tender conscience, them, themselves, they, twinge of conscience,
   unconscious, unconscious mind, vital impulse, voice of conscience,
   you, yours truly, yourself, yourselves