obbligato [ˌɒblɪˈgɑːtəʊ] ( 美 亦作 obligato) (pl. obbligatos 或 obbligati)
[usu. with or as modifier]an instrumental part, typically distinctive in effect, which is integral to a piece of music and should not be omitted in performance 助奏声部
语源
Italian, literally obligatory', from Latin obligatus, past participle of obligare (see oblige)