The authors agree that this surname is typically Sicilian and that it derives from a term related to the thistle, a spiny plant used to card wool —that is, to free it of impurities and knots before spinning—, which suggests that the founders of these family lines were dedicated to the textile work of wool.

E. Rossoni notes its presence in the Enna, Catania, Messina and Caltanissetta areas, as well as in Palermo, and points to a Greek origin of the nickname that gave rise to the surname. F. Miranda specifies that the word comes from the modern Greek spoken in the regions of the ancient Magna Graecia, and clarifies that cardo also designated the carding machine, a large cylinder covered with cards. Rossoni adds that the surname has specific presence in other regions of Italy, including Lombardy, Piedmont, Veneto, Lazio, Tuscany, Emilia-Romagna, Campania and Liguria.

V. Blunda connects the surname with the Sicilian dialectal word cardàci, meaning "thistle of the wool-workers", and places its origin in the context of traditional Sicilian wool-working, a relevant activity in areas of sheep grazing such as the Madonie and the Nebrodi, where the thistle was gathered to supply the textile workshops.