libretto
The text or script of an opera, oratorio, or musical.
In Depth
A libretto (Italian for little book) contains all the words that are sung and spoken in an opera, oratorio, or musical theatre work. The librettist is the author of this text, and the relationship between librettist and composer is one of the most important creative partnerships in music.
Some composers wrote their own libretti (Wagner most famously), but most collaborated with specialist writers. Mozart and Da Ponte produced three masterpieces together. Verdi worked with multiple librettists, often demanding extensive revisions. The quality of a libretto matters enormously — even the finest music cannot save a dramatically inept text.
Wagner wrote his own libretti for all his major operas, making him one of the few figures in history to have created both the words and music of an entire four-opera cycle lasting 15 hours.