The authors agree that this surname derives from the term gamba (leg in Italian), although they differ in the precise interpretation. E. De Felice holds that it originates in nicknames alluding to physical characteristics, deficiencies or jocular and polemical traits related to the legs, with medieval documentation from the 10th century in forms such as Gamba, Gambeta, Gambinus and Gambalracta. In a similar line, R. Brondolo links it to a nickname referring to "vigorous legs", and places it mainly in northern Italy.

E. Rossoni proposes, on the other hand, that the surname would derive from an abbreviated form of the Lombard name Gambara, without ruling out that in certain cases nicknames related to physical characteristics such as the speed or the length of the legs may also have operated. Rossoni describes a wide distribution: Gamba is very spread throughout northern Italy, with presence also in the Lucca, Pisa, Livorno, Pesaro, Rome, Latina, Naples and Cosenza areas. The variant Gambi is concentrated in the Ravenna area, with presence in those of Bologna, Forlì, Florence and Ancona. Gambe appears in the Reggio Calabria area, and Gambo is considered probably a transcription error.