party has 2 distinct synonyms spread across 2 of its 6 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.
an organization to gain political power
“in 1992 Perot tried to organize a third party at the national level”
a group of people gathered together for pleasure
“she joined the party after dinner”
a band of people associated temporarily in some activity
“they organized a party to search for food”
an occasion on which people can assemble for social interaction and entertainment
“he planned a party to celebrate Bastille Day”
a person involved in legal proceedings
“the party of the first part”
Synonyms, antonyms and the broader and narrower relations for party come from Princeton University’s WordNet. Full sources and licences.