conscience

What it means

1. countableuncountableThe 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.

   4 more examples

   1949, Albert Einstein, as quoted by Virgil Henshaw in Albert Einstein: Philosopher Scientist, Never do anything against conscience, even if the state demands it.

   As for Grierson, he poured liquor into himself as if it were so much soothing syrup, demonstrating that a good digestion is the highest form of good conscience.

   1938, Norman Lindsay, Age of Consent, 1st Australian edition, Sydney, N.S.W.: Ure Smith, published 1962, →OCLC, page 159

   [“]Twer is not a friend of mine testifying against me reluctantly and for conscience’ sake, as the prosecution would have you believe. He is a spy, performing his paid job.[”]

   1951, Isaac Asimov, Foundation, Panther Books Ltd, published 1974, part V: The Merchant Princes, chapter 14, page 175

   ‘Then the father has a great fight with his terrible conscience,’ said Munday with granite seriousness. ‘Should he make a row with the police […]? Or should he say nothing about it and condone brutality for fear of appearing in the newspapers?

   1963, Margery Allingham, chapter 18, in The China Governess: A Mystery, London: Chatto & Windus, →OCLC

2. countableuncountablefictionA 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. countableobsoleteuncountableConsciousness; thinking; awareness, especially self-awareness.

   Thus conscience does make cowards of us all; And thus the native hue of resolution Is sicklied o'er with the pale cast of thought.

   c. 1599–1602 (date written), William Shakespeare, “The Tragedie of Hamlet, Prince of Denmarke”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC, [Act III, scene i]

In a sentence

Your conscience is your highest authority.

Where it comes from

1. Latinconscientia“knowledge within oneself”
2. Old Frenchconscience
3. Middle Englishconscience
4. Englishconscience

From Middle English conscience, from Old French conscience, from Latin conscientia (“knowledge within oneself”) (a calque of Ancient Greek σῠνείδησῐς (sŭneídēsĭs)), from consciens, present participle of conscire (“to know, to be conscious (of wrong)”), from com- (“together”) + scire (“to know”).