Word parts serious + -ness Pronunciation (US) IPA (key): /ˈsɪriəsnəs/ (UK) IPA (key): /ˈsɪəriəsnəs/ Audio (UK)(file) Hyphenation: se‧ri‧ous‧ness Noun Singular seriousness Plural none The quality of being serious. His seriousness in his work is rather impressive. Related words seriousWikiwand - on Seamless Wikipedia browsing. On steroids.Remove ads