dunker has 2 distinct synonyms spread across 1 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.
an eater who dips food into a liquid before eating it
“he was a dunker--he couldn't eat a doughnut without a cup of coffee to dunk it in”
a basketball player who is able to make dunk shots
an adherent of Baptistic doctrines (who practice baptism by immersion)
Synonyms, antonyms and the broader and narrower relations for dunker come from Princeton University’s WordNet. Full sources and licences.