profession has 1 distinct synonym spread across 1 of its 4 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 body of people in a learned occupation
“the news spread rapidly through the medical profession”
an occupation requiring special education (especially in the liberal arts or sciences)
an open avowal (true or false) of some belief or opinion
“a profession of disagreement”
affirmation of acceptance of some religion or faith
“a profession of Christianity”
Synonyms, antonyms and the broader and narrower relations for profession come from Princeton University’s WordNet. Full sources and licences.