conscience has 3 distinct synonyms spread across 1 of its 3 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
motivation deriving logically from ethical or moral principles that govern a person's thoughts and actions
conformity to one's own sense of right conduct
“a person of unflagging conscience”
a feeling of shame when you do something immoral
“he has no conscience about his cruelty”
Synonyms, antonyms and the broader and narrower relations for conscience come from Princeton University’s WordNet. Full sources and licences.