noun / adjective
obbligato
ah-bluh-GAH-toh/ˌɑːblɪˈɡɑːtəʊ/
An accompanying musical part essential to a composition.
The aria requires a flute obbligato alongside the vocal melody.

Etymology
Binding became a figurative image for obligation: obbligato literally means “obligated.” In music, it marks an accompanying part as required rather than optional—important enough that it cannot be omitted.
In context
The jingling of our equipment, the squelching of boots in mud, the labored breathing of weary men, an occasional curse, was like an obbligato to the thunderous storm of war
More examples
- She plays the obbligato while the choir sings.
- The obbligato violin part cannot be left out.
- Both arias feature expressive oboe obbligatos.
Forms
obbligato · obbligatos · obbligati
Similar words
- accompaniment
- Supports the main musical part but is not necessarily indispensable.