Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
gentleman-at-arms is a noun meaning "one of 40 gentlemen who attend the British sovereign on state occasions". It carries one recorded sense.
one of 40 gentlemen who attend the British sovereign on state occasions
Definitions, synonyms and semantic relations for gentleman-at-arms come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.