alliance has 5 distinct synonyms spread across 4 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. 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 connection based on kinship or marriage or common interest
“the shifting alliances within a large family”
an organization of people (or countries) involved in a pact or treaty
a formal agreement establishing an association or alliance between nations or other groups to achieve a particular aim
Synonyms, antonyms and the broader and narrower relations for alliance come from Princeton University’s WordNet. Full sources and licences.