battle of the little bighorn has 3 distinct synonyms spread across 1 of its 1 sense. 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 battle in Montana near the Little Bighorn River between United States cavalry under Custer and several groups of Native Americans (1876); Custer was pursuing Sioux led by Sitting Bull; Custer underestimated the size of the Sioux forces (which were supported by Cheyenne warriors) and was killed along with all his command
Synonyms, antonyms and the broader and narrower relations for battle of the little bighorn come from Princeton University’s WordNet. Full sources and licences.