disintegration 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 loss (or serious disruption) of organization in some system
“a disintegration of personality”
separation into component parts
the spontaneous disintegration of a radioactive substance along with the emission of ionizing radiation
total destruction
“bomb tests resulted in the annihilation of the atoll”
Synonyms, antonyms and the broader and narrower relations for disintegration come from Princeton University’s WordNet. Full sources and licences.