Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
unimaginably is an adverb meaning "to an unimaginable extent". It carries one recorded sense.
to an unimaginable extent
Definitions, synonyms and semantic relations for unimaginably come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.