chant has 4 distinct synonyms spread across 2 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.
recite with musical intonation; recite as a chant or a psalm
“The rabbi chanted a prayer”
utter monotonously and repetitively and rhythmically
“The students chanted the same slogan over and over again”
Synonyms, antonyms and the broader and narrower relations for chant come from Princeton University’s WordNet. Full sources and licences.
a repetitive song in which as many syllables as necessary are assigned to a single tone