WordNet records no synonym and no antonym for chihuahua. 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.
a city in northern Mexico in the state of Chihuahua; commercial center of northern Mexico
a state in northern Mexico; mostly high plateau
an old breed of tiny short-haired dog with protruding eyes from Mexico held to antedate Aztec civilization
Synonyms, antonyms and the broader and narrower relations for chihuahua come from Princeton University’s WordNet. Full sources and licences.