slide has 15 distinct synonyms spread across 8 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.
a small flat rectangular piece of glass on which specimens can be mounted for microscopic study
plaything consisting of a sloping chute down which children can slide
the act of moving smoothly along a surface while remaining in contact with it
“his slide didn't stop until the bottom of the hill”
a transparency mounted in a frame; viewed with a slide projector
sloping channel through which things can descend
move smoothly along a surface
“He slid the money over to the other gambler”
Synonyms, antonyms and the broader and narrower relations for slide come from Princeton University’s WordNet. Full sources and licences.