gens

In ancient Rome, a gens was a family consisting of individuals who shared the same nomen gentilicium and who claimed descent from a common ancestor. A branch of a gens, sometimes identified by a distinct cognomen, was called a stirps. For example, in the name Marcus Tullius Cicero, Tullius is the nomen gentilicium, which identifies Cicero as a member of the Tullia gens, while the surname Cicero identifies the branch of the gens to which he belonged.