say it: NAHY-snuhs
niceness is a noun meaning "a courteous manner that respects accepted social usage". It carries 3 recorded senses.
a courteous manner that respects accepted social usage
the quality of nice
the quality of being difficult to detect or analyze
“you had to admire the subtlety of the distinctions he drew”
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 niceness come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.