Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
gradualness is a noun meaning "the property possessed by a slope that is very gradual". It carries 2 recorded senses.
the property possessed by a slope that is very gradual
the quality of being gradual or of coming about by gradual stages
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for gradualness come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.