Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
roundness is a noun meaning "the fullness of a tone of voice". It carries 4 recorded senses.
the quality of being round numbers
“he gave us the results in round numbers, but their roundness didn't affect the point he was making”
the property possessed by a line or surface that is curved and not angular
the bodily property of being well rounded
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 roundness come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.