canvas has 4 distinct synonyms spread across 6 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.
a large piece of fabric (usually canvas fabric) by means of which wind is used to propel a sailing vessel
cover with canvas
“She canvassed the walls of her living room so as to conceal the ugly cracks”
Synonyms, antonyms and the broader and narrower relations for canvas come from Princeton University’s WordNet. Full sources and licences.