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.