E. De Stefani notes that it is a Friulian microtoponymic surname derived from the numerous place names of the ortis 'orti' type, in turn from the Latin hortus, "garden, vegetable plot". The place name is attested as a place name at Vito d'Asio, Preone and at Fusea —a hamlet of Tolmezzo— from the beginning of the 16th century, and in the vicinity of Clauzetto the variant Orton, of the same base, is also documented. In time, these place names became a surname.

De Stefani documents the surname especially in Carnia —the mountainous area of northern Friuli, in the province of Udine—, with a notable presence at Paluzza and at Treppo Carnico (today Treppo Ligosullo), and attestations at Enemonzo, Arta Terme and Preone from the 18th century, as well as at Treppo from the beginning of the 17th century and at Vito d'Asio from the middle of the same century. He also notes that the surname is known in Italian literary culture for being that of the protagonist of Le ultime lettere di Jacopo Ortis, a canonical novel by Ugo Foscolo.

E. Rossoni agrees with the Latin microtoponymic origin for the Friulian core, in the Udine area, but further identifies two southern foci: one in the Lecce area —in Puglia— and another between the Trapani and Agrigento areas —in Sicily—. For these last, Rossoni proposes a Spanish or Catalan origin, deriving from the surname Ortiz, a patronymic form in -iz from a modification with suppression of the initial sound of the Latin name Fortis.