tread has 4 distinct synonyms spread across 3 of its 10 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.
crush as if by treading on
“tread grapes to make wine”
brace (an archer's bow) by pressing the foot against the center
mate with
“male birds tread the females”
the grooved surface of a pneumatic tire
the part (as of a wheel or shoe) that makes contact with the ground
structural member consisting of the horizontal part of a stair or step
Synonyms, antonyms and the broader and narrower relations for tread come from Princeton University’s WordNet. Full sources and licences.