sequestration has 2 distinct synonyms spread across 2 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.
the act of segregating or sequestering
“sequestration of the jury”
the action of forming a chelate or other stable compound with an ion or atom or molecule so that it is no longer available for reactions
Synonyms, antonyms and the broader and narrower relations for sequestration come from Princeton University’s WordNet. Full sources and licences.
a writ that authorizes the seizure of property
seizing property that belongs to someone else and holding it until profits pay the demand for which it was seized