The authors agree that this surname derives from the dialectal term camastra (or camastro), which designates the chain from which pots are hung over the hearth fire, coming in turn from the Greek κρεμάστρα ("hanger", "hearth chain"). It functioned originally as a nickname referring to some trait associated with that domestic utensil, and over time became a surname along the family line.

E. Rossoni adds a second hypothesis: the surname could derive from the Phoenician name Kamastart, also associated with a deity, although this proposal is more controversial. Rossoni also notes presence of the surname in the Bari area —especially in Grumo Appula, Castellana Grotte and Altamura—, in the Frosinone area and in Rome.

G. Rohlfs emphasises the Greek-Byzantine origin of the surname and documents it in localities of the Catanzaro area such as Botricello, Stalettì and Vallefiorita, interpreting it as a reflection of the Byzantine presence in southern Italy. V. Blunda confirms the Greek etymology and places the surname in Sicily, where the locality Camastra, in the Palermo area, is also recorded.