WordNet records no synonym and no antonym for airbrush. 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.
an atomizer to spray paint by means of compressed air
paint with an airbrush
“The old car looks like new now that we airbrushed it”
Synonyms, antonyms and the broader and narrower relations for airbrush come from Princeton University’s WordNet. Full sources and licences.