Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
deucedly is an adverb meaning "(used as intensives) extremely". It carries one recorded sense.
(used as intensives) extremely
“she was madly in love”
“deadly dull”
“deadly earnest”
“deucedly clever”
“insanely jealous”
intensifier
Definitions, synonyms and semantic relations for deucedly come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.