discount has 11 distinct synonyms spread across 5 of its 6 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 act of reducing the selling price of merchandise
interest on an annual basis deducted in advance on a loan
bar from attention or consideration
“She dismissed his advances”
Synonyms, antonyms and the broader and narrower relations for discount come from Princeton University’s WordNet. Full sources and licences.