WordNet records no synonym and no antonym for acceptor. It is the only member of each of its synsets, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
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.
(chemistry) in the formation of a coordinate bond it is the compound to which electrons are donated
the person (or institution) who accepts a check or draft and becomes responsible for paying the party named in the draft when it matures
Synonyms, antonyms and the broader and narrower relations for acceptor come from Princeton University’s WordNet. Full sources and licences.