Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
deceitfully is an adverb meaning "in a corrupt and deceitful manner". It carries one recorded sense.
in a corrupt and deceitful manner
“he acted dishonestly when he gave the contract to his best friend”
Definitions, synonyms and semantic relations for deceitfully come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.