noun
libretto
lih-BRET-oh/lɪˈbretəʊ/
The words or script of an opera, musical, or other vocal work.
The opera singer studies the libretto beside the musical score.

Etymology
Literally a “little book,” a libretto named the book containing the words of an extended musical work. The name also applies to the words themselves, rather than just their printed container.
In context
… if it were spoken it would be just as successful as the libretto …
More examples
- She writes both the music and the libretto for her opera.
- The musical's libretto includes dialogue between the songs.
- English translations of the libretti appear beside the Italian texts.
Forms
libretto · librettos · libretti
librettist noun — A writer of operatic or musical texts.