(It.; Fr. obligé; Ger. obligat).
Indispensable. Adjective attached to the name of an instr., e.g. ‘vc. obbligato’, where the instr.'s part is obligatory, and special or unusual in effect. To use the term in the opposite sense of optional or ad libitum is wrong, as is the frequently‐encountered spelling obligato (favoured by Britten).