floater has 8 distinct synonyms spread across 3 of its 8 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.
spots before the eyes caused by opaque cell fragments in the vitreous humor and lens
“floaters seem to drift through the field of vision”
a debt instrument with a variable interest rate tied to some other interest rate (e.g. the rate paid by T-bills)
a wanderer who has no established residence or visible means of support
an employee who is reassigned from job to job as needed
a voter who votes illegally at different polling places in the same election
an insurance policy covering loss of movable property (e.g. jewelry) regardless of its location
Synonyms, antonyms and the broader and narrower relations for floater come from Princeton University’s WordNet. Full sources and licences.