fictional has 3 distinct synonyms spread across 1 of its 2 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 nonfictional.
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.
related to or involving literary fiction
“clever fictional devices”
formed or conceived by the imagination
“a fabricated excuse for his absence”
Synonyms, antonyms and the broader and narrower relations for fictional come from Princeton University’s WordNet. Full sources and licences.