E. De Felice notes that the surname was formed from the place name Gaeta —in southern use Gaìta— and from its gentilic Gaetano, which continues mainly the personal name Gaetano, which goes back to the Latin ethnic cognomen Caietanus, meaning "inhabitant or native of Gaeta".

E. Rossoni derives the surname from the name of the peninsula of Gaeta, although he also considers possible a derivation from place names originated in the Greek word kaièta, which designates a small bay or cove. He considers much less probable the hypothesis that links it with the Greek name Kaieta, corresponding to the nurse of Aeneas according to mythological tradition. The surname is very spread in southern Italy, with greater concentration in Campania and in the Naples area.