Libretto is the singular. Libretti is the plural. Sometimes librettos is also commonly used as the plural.
I don't know I'm so sorry!
librettos
Plural form of Libretto is Libretti.
Libretto (singular) or Libretti (plural)
Librettos
Libretto is the text to an Opera.
Libretto.
The singular form of the demonstrative pronoun 'these' is this.
The libretto is the text - the lyrics - which the composer adds music to. The score is the music on which the libretto is sung.
The singular form of "that" is "it."
"Libretto" is the technical term for the text and lyrics.
The singular form of "cuffs" is cuff.