1.NounThe ethical or moral sense of right and wrong, chiefly as it affects a person’s own behaviour and forms their attitude to their past actions.
"Your conscience is your highest authority."
2.NounA personification of the moral sense of right and wrong, usually in the form of a person, a being or merely a voice that gives moral lessons and advices.
3.NounConsciousness; thinking; awareness, especially self-awareness.