float has 9 distinct synonyms spread across 5 of its 16 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. Its one recorded opposite is sink.
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.
circulate or discuss tentatively; test the waters with
“The Republicans are floating the idea of a tax reform”
make the surface of level or smooth
“float the plaster”
allow (currencies) to fluctuate
“The government floated the ruble for a few months”
convert from a fixed point notation to a floating point notation
“float data”
the time interval between the deposit of a check in a bank and its payment
the number of shares outstanding and available for trading by the public
a drink with ice cream floating in it
an elaborate display mounted on a platform carried by a truck (or pulled by a truck) in a procession or parade
a hand tool with a flat face used for smoothing and finishing the surface of plaster or cement or stucco
an air-filled sac near the spinal column in many fishes that helps maintain buoyancy
Synonyms, antonyms and the broader and narrower relations for float come from Princeton University’s WordNet. Full sources and licences.