E. Rossoni notes that the surname presents two independent clusters of origin: one located in Grottaglie, in the Taranto area, and another in the area of the Strait of Messina. Rossoni proposes that both forms, Cardea and Cardia, would derive from nicknames linked to the Greek word kardia ("heart"), although in some cases they could come from homonymous Greek place names, such as the city of Kardia in Thrace. The first documentations of its transformation into a surname are recorded in the Locri area from the 17th century.

V. Blunda, on the other hand, proposes a different etymology: the surname would come from the Greek carydèa, "walnut", and would have functioned as a nickname applied to the ancestor for his proximity to a walnut tree or for some trait associated with that fruit, before becoming a surname within the onomastics of southern Italy.

Rossoni adds that the variant Cardia has its main presence in the south of Sardinia and another area in the Messina area, and is documented on that island from medieval times, among the signatories of the Peace of Eleonora of 1388.