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.
The singular form of the demonstrative pronoun 'these' is this.
The singular form of "that" is "it."
The singular form is cuff.
it is already in its singular form.
Libretto.
"Stratum" is the singular form of stratum. The plural form is "strata".