Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
masterless is an adjective meaning "having no lord or master". It carries one recorded sense.
having no lord or master
“harsh punishments for sturdy vagabonds and masterless men”
Definitions, synonyms and semantic relations for masterless come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.