WordNet records no synonym and no antonym for rollerblade. It is the only member of each of its synsets, 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.
travel on shoes with a single line of rubber wheels attached to their soles
“you'd better wear a helmet and knee protectors when you Rollerblade!”
Synonyms, antonyms and the broader and narrower relations for rollerblade come from Princeton University’s WordNet. Full sources and licences.