Libretto: All words sung

Quasi libretto (my term): All words sung and a few sung

Libretto; and script: All words sung; and all words spoken


But, really, librettos should include all the lyrics for the songs and recitatives in an opera, shouldn't they? I guess it's come to mean something different, but, strictly speaking, are librettos and their inclusive lyrics really from the world of opera?

Really wondering what they are,
OrB