highlight has 5 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.
move into the foreground to make more visible or prominent
“The introduction highlighted the speaker's distinguished career in linguistics”
apply a highlighter to one's cheeks or eyebrows in order to make them more prominent
“highlight the area above your eyebrows”
Synonyms, antonyms and the broader and narrower relations for highlight come from Princeton University’s WordNet. Full sources and licences.