emphasis has 3 distinct synonyms spread across 3 of its 4 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.
special importance or significance
“the red light gave the central figure increased emphasis”
Synonyms, antonyms and the broader and narrower relations for emphasis come from Princeton University’s WordNet. Full sources and licences.
special and significant stress by means of position or repetition e.g.
the relative prominence of a syllable or musical note (especially with regard to stress or pitch)
“he put the stress on the wrong syllable”