hertz has 9 distinct synonyms spread across 3 of its 3 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.
the unit of frequency; one hertz has a periodic interval of one second (named for Heinrich Rudolph Hertz)
German physicist who was the first to produce electromagnetic waves artificially (1857-1894)
German physicist who with James Franck proved the existence of the stationary energy states postulated by Bohr (1887-1975)
Synonyms, antonyms and the broader and narrower relations for hertz come from Princeton University’s WordNet. Full sources and licences.