Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
simpleness is a noun meaning "a lack of penetration or subtlety". It carries 4 recorded senses.
a lack of penetration or subtlety
“they took advantage of her simplicity”
the quality of being simple or uncompounded
“the simplicity of a crystal”
freedom from difficulty or hardship or effort
“he rose through the ranks with apparent ease”
“they put it into containers for ease of transportation”
“the very easiness of the deed held her back”
lack of ornamentation
“the room was simply decorated with great restraint”
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 simpleness come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.