broom has 5 distinct synonyms spread across 2 of its 5 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 cleaning implement for sweeping; bundle of straws or twigs attached to a long handle
any of various shrubs of the genera Cytisus or Genista or Spartium having long slender branches and racemes of yellow flowers
common Old World heath represented by many varieties; low evergreen grown widely in the northern hemisphere
Synonyms, antonyms and the broader and narrower relations for broom come from Princeton University’s WordNet. Full sources and licences.