vocalise
piece of music, usually for a solo voice (mostly soprano), performed without words only in vowels, with instrumental accompaniment, as well as musical compositions for this kind of works
en-US/ˈvoʊˌkʌlaɪz/
en-GB/ˈvəʊkəˌlaɪz/
piece of music, usually for a solo voice (mostly soprano), performed without words only in vowels, with instrumental accompaniment, as well as musical compositions for this kind of works