WordNet records no synonym and no antonym for leapfrog. 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.
advancing as if in the child's game, by leaping over obstacles or competitors
“the company still believes the chip is a leapfrog in integration and will pay huge dividends”
a game in which one child bends down and another leaps over
Synonyms, antonyms and the broader and narrower relations for leapfrog come from Princeton University’s WordNet. Full sources and licences.