reward has 9 distinct synonyms spread across 6 of its 8 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. Its one recorded opposite is penalty.
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.
a recompense for worthy acts or retribution for wrongdoing
“the wages of sin is death”
payment made in return for a service rendered
an act performed to strengthen approved behavior
Synonyms, antonyms and the broader and narrower relations for reward come from Princeton University’s WordNet. Full sources and licences.