E. Rossoni considers that the surname would derive from a nickname based on the dialectal term facci longo, meaning "long, thin and narrow face", which would have characterised the founder of the lineage. He places it as peculiar to Puglia, with specific zones in Bari and in Lucera, in the province of Foggia.

V. Blunda studies it as a Sicilian surname of dialectal origin, formed from the compound fàcci lònga, with the same meaning of "long face, elongated countenance". He notes that this type of descriptive nickname, applied to an ancestor identifiable by a distinctive facial trait, is a frequent motivation in Sicilian somatic surnames, and that it was transmitted from generation to generation as a family nickname until it became a surname.

Both authors agree, then, on the nickname origin and on the meaning of the base dialectal term, although they differ on the location: Rossoni links it to Puglia and Blunda to Sicily. The surname therefore presents independent origins in different regions of Italy.