WordNet records no synonym and no antonym for urban legend. It is the only member of its synset, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
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.
a story that appears mysteriously and spreads spontaneously in various forms and is usually false; contains elements of humor or horror and is popularly believed to be true
Synonyms, antonyms and the broader and narrower relations for urban legend come from Princeton University’s WordNet. Full sources and licences.