forfeit has 9 distinct synonyms spread across 5 of its 5 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 claim.
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 penalty for a fault or mistake that involves losing or giving up something
“the contract specified forfeits if the work was not completed on time”
the act of losing or surrendering something as a penalty for a mistake or fault or failure to perform etc.
surrendered as a penalty
Synonyms, antonyms and the broader and narrower relations for forfeit come from Princeton University’s WordNet. Full sources and licences.