WordNet records no synonym and no antonym for dimetapp. 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.
trade name for a drug containing an antihistamine and a decongestant; used to relieve nasal congestion and to treat rhinitis
Synonyms, antonyms and the broader and narrower relations for dimetapp come from Princeton University’s WordNet. Full sources and licences.