E. Rossoni derives this surname from a nickname based on the Sardinian word calamidade, "calamity", and notes it as peculiar to the Cagliari area.

V. Blunda proposes a different etymology, of Greek origin: calamìdas, a diminutive of kálamos, "reed", with the sense of "little reed". According to Blunda, the term functioned as a nickname applied to the ancestor linked to the reed, and he documents it in Sicily together with the parallel surname Calamia. The variant Calamita would represent a graphic adaptation of the same Greek etymon.