I. ˌä-blə-ˈgä-(ˌ)tō adjective
Etymology: Italian, obligatory, from past participle of obbligare to oblige, from Latin obligare — more at oblige
Date: 1794
: not to be omitted : obligatory — used as a direction in music; compare ad libitum
II. noun
( plural -tos also ob·bli·ga·ti -ˈgä-tē)
Date: 1839
1. : an elaborate especially melodic part accompanying a solo or principal melody and usually played by a single instrument
a song with violin obbligato
2. : accompaniment 2b ; especially : an attendant background sound