The thief must have had an attack of conscience, because he returned the wallet with nothing missing from it.
… it is a politician's natural instinct to avoid taking any stand that seems controversial unless and until the voters demand it or conscience absolutely requires it. —Al Gore, An Inconvenient Truth, 2006
We like to imagine literature as the still, small voice of human conscience. It is that only rarely, however. Actively and passively, it has always borne along pernicious ideas. —Marilynne Robinson, New York Times Book Review, 15 Mar. 1987
The rat had no morals, no —conscience, no scruples, no consideration, no decency … —E. B. White, Charlotte's Web, 1952
So she had lied to him, but so had he to her, they were quits on that score and his conscience was calm. —Bernard Malamud, The Magic Barrel, (1950) 1958
Middle English, from Anglo-French, from Latin conscientia, from conscient-, consciens, present participle of conscire to be conscious, be conscious of guilt, from com- + scire to know — more at science
: a sense of right and wrong and a feeling that what is right should be done <Her conscience told her to tell the truth.>
Word Root of CONSCIENCE
The Latin word scīre, meaning “to know” or “to understand,” gives us the root sci. Words from the Latin scīre have something to do with knowing or understanding. Science is the understanding of the world and how everything in it works. A person's conscience is the knowledge of right and wrong and the feeling that he or she should do right. Anything that is conscious knows what it is feeling.
Medical Definition of CONSCIENCE
: the part of the superego in psychoanalysis that transmits commands and admonitions to the ego