scratch has 49 distinct synonyms spread across 15 of its 17 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a competitor who has withdrawn from competition
a line indicating the location of the start of a race or a game
a harsh noise made by scraping
“the scrape of violin bows distracted her”
poor handwriting
(golf) a handicap of zero strokes
“a golfer who plays at scratch should be able to achieve par on a course”
cut the surface of; wear away the surface of
Synonyms, antonyms and the broader and narrower relations for scratch come from Princeton University’s WordNet. Full sources and licences.
gather (money or other resources) together over time
“She had scraped together enough money for college”