Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
faithlessly is an adverb meaning "in a disloyal and faithless manner". It carries one recorded sense.
in a disloyal and faithless manner
“he behaved treacherously”
“his wife played him false”
Definitions, synonyms and semantic relations for faithlessly come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.