The authors agree that this surname derives from the Latin given name Laetitia (masculine Laetitius), meaning "most happy" or, in more general terms, alluding to joy and happiness. It is a name of an auspicious character, that is, chosen for its good omen.

A. Bongioanni notes that it is a name of Italic origin with a self-evident meaning, and observes that in France it is usually written in the Latin form Laetitia and pronounced in the French manner. He adds that it does not appear in the calendar of saints.

E. Rossoni documents several related forms. The variant Letizi shows areas of concentration in the province of Pesaro —specifically in Cartoceto, Fano and Mondolfo— and in Rome. The form Letizia appears widely spread in Rome, in the provinces of Naples and Caserta, in Puglia —especially in the provinces of Taranto, Brindisi and Lecce— and in Sicily, with the greatest presence in the Messina area. The variant Letizio, by contrast, is extremely rare and would appear to be proper to Campania.