ariosoPronunciation: /ˌarɪˈəʊzəʊ, -səʊ/Definition of arioso noun (plural ariosos) [mass noun] Music (especially in opera and oratorio) vocal music that is more melodic than recitative but less formal than an aria: short passages of arioso [count noun]:his final arioso was more assured [as modifier]:these anthems contain arioso writingOrigin:Italian, from ariaarioso in other Oxford dictionaries Definition of arioso in the US English dictionary