The authors agree that the surname refers, at its base, to the Latin term terminus, meaning "boundary" or "frontier". However, each develops different aspects according to the region of analysis.

E. De Stefani notes that in Ampezzo, a locality of the Carnia —a mountainous zone of northern Friuli, in the province of Udine—, the surname comes from the dialectal word tèrmin, which designates the boundary or mark of demarcation between properties (stakes, stones). He adds that a connection has also been proposed with the Friulian toponymic type Termenét, Tormenét, linked to the Venetan tórmene ("isolated rounded height"), though probably with a semantic crossing with the notion of "boundary".

E. Rossoni considers that Termine has independent stems in the north of the Bari area and in the west of Sicily. The variant Termini, on the other hand, shows a wider distribution throughout Sicily, besides smaller nuclei in Friuli, the Perugia area and Rome. In Sicily, both forms would derive from place names such as Termini Imerese or Casteltermini. Rossoni also documents a historical record: a Matteo, master of accountancy, mentioned in the year 1283.