visitation has 2 distinct synonyms spread across 1 of its 3 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.
an annoying or frustrating or catastrophic event
“his mother-in-law's visits were a great trial for him”
any disaster or catastrophe
“a visitation of the plague”
an official visit for inspection or supervision
“the commissioner made visitations to all the precinct stations”
Synonyms, antonyms and the broader and narrower relations for visitation come from Princeton University’s WordNet. Full sources and licences.