sorrel has 11 distinct synonyms spread across 5 of its 6 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.
any of certain coarse weedy plants with long taproots, sometimes used as table greens or in folk medicine
East Indian sparsely prickly annual herb or perennial subshrub widely cultivated for its fleshy calyxes used in tarts and jelly and for its bast fiber
large sour-tasting arrowhead-shaped leaves used in salads and sauces
a horse of a brownish orange to light brown color
of a light brownish color
Synonyms, antonyms and the broader and narrower relations for sorrel come from Princeton University’s WordNet. Full sources and licences.