Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
incontrovertibly is an adverb meaning "in an obvious and provable manner". It carries one recorded sense.
in an obvious and provable manner
“his documentary sources are demonstrably wrong”
Definitions, synonyms and semantic relations for incontrovertibly come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.