D defs.my
Entry 1 sense Webster, 1913

Libretto

/(lĭ*brĕt"tō̇; It. lē̇*brā̇t"tō̇)/ · Li·bret·to · IPA /lɪˈbɹɛt.oʊ/
01 n. A book containing the words of an opera or extended piece of music.
pl. Librettos, Libretti ((-tōz))
  1. 1.
    A book containing the words of an opera or extended piece of music.(Mus.)