convert has 6 distinct synonyms spread across 4 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.
change from one system to another or to a new plan or policy
“We converted from 220 to 110 Volt”
change religious beliefs, or adopt a religious belief
“She converted to Buddhism”
cause to adopt a new or different faith
“The missionaries converted the Indian population”
score an extra point or points after touchdown by kicking the ball through the uprights or advancing the ball into the end zone
“Smith converted and his team won”
complete successfully
“score a penalty shot or free throw”
change in nature, purpose, or function; undergo a chemical change
“The substance converts to an acid”
Synonyms, antonyms and the broader and narrower relations for convert come from Princeton University’s WordNet. Full sources and licences.