possible 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. Its one recorded opposite is impossible.
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.
something that can be done
“politics is the art of the possible”
an applicant who might be suitable
Synonyms, antonyms and the broader and narrower relations for possible come from Princeton University’s WordNet. Full sources and licences.
capable of happening or existing
“a breakthrough may be possible next year”