ghost has 11 distinct synonyms spread across 5 of its 7 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 visible disembodied soul of a dead person
move like a ghost
“The masked men ghosted across the moonlit yard”
Synonyms, antonyms and the broader and narrower relations for ghost come from Princeton University’s WordNet. Full sources and licences.
write for someone else
“How many books have you ghostwritten so far?”