pay has 13 distinct synonyms spread across 6 of its 12 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.
convey, as of a compliment, regards, attention, etc.; bestow
“Don't pay him any mind”
do or give something to somebody in return
“Does she pay you for the work you are doing?”
be worth it
“It pays to go through the trouble”
bear (a cost or penalty), in recompense for some action
“You'll pay for this!”
make a compensation for
“a favor that cannot be paid back”
something that remunerates
“wages were paid by check”
Synonyms, antonyms and the broader and narrower relations for pay come from Princeton University’s WordNet. Full sources and licences.