irresponsibility n. + Add to list US //ˌɪɹəˌspɑnsəˈbɪɫəti// UK //ɪɹɪspˌɒnsəbˈɪlɪti// ir·re·spon·si·bil·i·ty SynonymsAntonymsEtymology Synonyms irresponsibleness Antonyms responsibilityresponsiblenessOrigin From ir- + responsibility or irresponsible + -ity.