WordNet records no synonym and no antonym for bombardier. 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 noncommissioned officer in the British artillery
the member of a bomber crew responsible for using the bombsight and releasing the bombs on the target
Synonyms, antonyms and the broader and narrower relations for bombardier come from Princeton University’s WordNet. Full sources and licences.