WordNet records no synonym and no antonym for mason wasp. 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.
solitary wasp that constructs nests of hardened mud or clay for the young
any of various solitary wasps that construct nests of hardened mud for their young
Synonyms, antonyms and the broader and narrower relations for mason wasp come from Princeton University’s WordNet. Full sources and licences.