Libretto \Li*bret"to\ (l[i^]*br[e^]t"t[-o]; It. l[-e]*br[asl]t"t[-o]), n.; pl. E. {Librettos} (-t[=o]z), It. {Libretti} (-t[-e]). [It., dim. of libro book, L. liber. See {Libel}.] (Mus.) (a) A book containing the words of an opera or extended piece of music. (b) The words themselves. [1913 Webster]