Italian language

Italian was a language spoken on the planet Earth, originating from Latin in the nation-state of Italy.

When Sybok the God of Sha Ka Ree he inquired "Qual sei tu", which mean "Who art thou" in Italian. 

Leonardo da Vinci in the holodeck program created by Kathryn Janeway, as well as various others, occasionally spoke Italian:

Background
The Star Trek: Voyager episode title is Italian, meaning virtuous or master.