conscience

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An awareness of morality in regard to one's behavior; a sense of right and wrong that urges one to act morally.
• noun A source of moral or ethical judgment or pronouncement.
• noun Conformity to one's own sense of right conduct.
• noun The part of the superego in psychoanalysis that judges the ethical nature of one's actions and thoughts and then transmits such determinations to the ego for consideration.
• noun Obsolete Consciousness or awareness of something.
• idiom (in (all good) conscience) In all fairness; by any reasonable standard.
• idiom (on (one's) conscience) Causing one to feel guilty or uneasy.

from The Century Dictionary.

• noun Consciousness; knowledge.
• noun Private or inward thoughts; real sentiments.
• noun The consciousness that the acts for which a person believes himself to be responsible do or do not conform to his ideal of right; the moral judgment of the individual applied to his own conduct, in distinction from his perception of right and wrong in the abstract, and in the conduct of others.
• noun Moral sense; scrupulosity; conformity to one's own sense of right in conduct, or to that of the community.
• noun Tender feeling; pity.
• noun Same as breastplate, A bellarmine.
• noun Most certainly; assuredly.

from the GNU version of the Collaborative International Dictionary of English.

• noun obsolete Knowledge of one's own thoughts or actions; consciousness.
• noun The faculty, power, or inward principle which decides as to the character of one's own actions, purposes, and affections, warning against and condemning that which is wrong, and approving and prompting to that which is right; the moral faculty passing judgment on one's self; the moral sense.
• noun The estimate or determination of conscience; conviction or right or duty.
• noun obsolete Tenderness of feeling; pity.
• noun a clause in a general law exempting persons whose religious scruples forbid compliance therewith, -- as from taking judicial oaths, rendering military service, etc.
• noun stolen or wrongfully acquired money that is voluntarily restored to the rightful possessor. Such money paid into the United States treasury by unknown debtors is called the Conscience fund.
• noun [Eng.] a court established for the recovery of small debts, in London and other trading cities and districts.
• noun in deference or obedience to conscience or reason; in reason; reasonably.
• noun to act according to the dictates of conscience concerning (any matter), or to scruple to act contrary to its dictates.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The moral sense of right and wrong, chiefly as it affects one's own behaviour; inwit.
• noun A 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.
• noun obsolete Consciousness; thinking; awareness, especially self-awareness.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun conformity to one's own sense of right conduct
• noun motivation deriving logically from ethical or moral principles that govern a person's thoughts and actions
• noun a feeling of shame when you do something immoral