fleet has 9 distinct synonyms spread across 3 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.
group of aircraft operating together under the same ownership
group of motor vehicles operating together under the same ownership
a group of steamships operating together under the same ownership
a group of warships organized as a tactical unit
move along rapidly and lightly; skim or dart
“The hummingbird flitted among the branches”
Synonyms, antonyms and the broader and narrower relations for fleet come from Princeton University’s WordNet. Full sources and licences.