wool grass has 3 distinct synonyms spread across 2 of its 2 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.
sedge of eastern North America having numerous clustered woolly spikelets
grass often cultivated for its long white-ribbed leaves and large plumes resembling those of pampas grass
Synonyms, antonyms and the broader and narrower relations for wool grass come from Princeton University’s WordNet. Full sources and licences.