battle has 5 distinct synonyms spread across 4 of its 4 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.
a hostile meeting of opposing military forces in the course of a war
“Grant won a decisive victory in the battle of Chickamauga”
Synonyms, antonyms and the broader and narrower relations for battle come from Princeton University’s WordNet. Full sources and licences.
an open clash between two opposing groups (or individuals)
“the harder the conflict the more glorious the triumph”