What is the X in X-mas?
early 13c., from Old French conscience "conscience, innermost thoughts, desires, intentions; feelings" (12c.), from Latin conscientia "knowledge within oneself, sense of right, a moral sense," from conscientem (nominative consciens), present participle of conscire "be (mutually) aware," from com- "with," or "thoroughly" (see com-) + scire "to know" (see science).
Probably a loan-translation of Greek syneidesis, literally "with-knowledge." Sometimes nativized in Old English/Middle English as inwit. Russian also uses a loan-translation, so-vest, "conscience," literally "with-knowledge."
conscience con·science (kŏn'shəns)
The awareness of a moral or ethical aspect to one's conduct together with the urge to prefer right over wrong.
The part of the superego that judges the ethical nature of one's actions and thoughts and then transmits such determinations to the ego for consideration.
that faculty of the mind, or inborn sense of right and wrong, by which we judge of the moral character of human conduct. It is common to all men. Like all our other faculties, it has been perverted by the Fall (John 16:2; Acts 26:9; Rom. 2:15). It is spoken of as "defiled" (Titus 1:15), and "seared" (1 Tim. 4:2). A "conscience void of offence" is to be sought and cultivated (Acts 24:16; Rom. 9:1; 2 Cor. 1:12; 1 Tim. 1:5, 19; 1 Pet. 3:21).
a personal sense of the moral content of one's own conduct, intentions, or character with regard to a feeling of obligation to do right or be good. Conscience, usually informed by acculturation and instruction, is thus generally understood to give intuitively authoritative judgments regarding the moral quality of single actions