The surname Firpo, together with others such as Filippi, Filippo, Filpo, Lippo, Lippi and their variants, has its origin in the medieval personal name Filippo. This name is the Italian form of the Greek Philippos, composed of phílos ("friend") and híppos ("horse"), with the sense of "the one who loves horses" or "friend of horses".

The name spread widely throughout Italy from the High Middle Ages, driven by the veneration of the Apostle Saint Philip, one of the twelve disciples, and later by the enormous popular devotion to Saint Philip Neri (16th century), a central figure of Italian spirituality. Because of this, Filippo became one of the most used given names for centuries, generating numerous family, regional and patronymic forms, which later gave rise to surnames.

In everyday speech, the name underwent phonetic reductions and affective forms. In different regions variants arose such as:

• Filippi → literally "the sons (or descendants) of Filippo".
• Filippo / Filipo → direct form of the original name.
• Filpo → popular abbreviated form.
• Firpo → Ligurian and Piedmontese evolution of Filpo, with the fall of the central vowel.
• Lippo / Lippi → medieval affective hypocoristic forms, very frequent in Tuscany and Emilia.

These transformations show how, from the same personal name deeply rooted in the Christian tradition, distinct surnames arose according to dialect, region and local history.

Thus, Firpo should be understood not as an isolated surname, but as part of a very ancient onomastic family, whose common trunk is the name Filippo, spread in Italy for more than a thousand years.