Nomen gentilicium

The nomen gentilicium (or simply nomen) was a hereditary name borne by the peoples of Roman Italy and later by the citizens of the Roman Republic and the Roman Empire. It was originally the name of one's gens (family or clan) by patrilineal descent. However, as Rome expanded its frontiers and non-Roman peoples were progressively granted citizenship and concomitant nomen, the latter lost its value in indicating patrilineal ancestry.

For men, the nomen was the middle of the tria nomina ("three names"), after the praenomen and before the cognomen. For women, the nomen was often the only name used until the late Republic. For example, three members of gens Julia were Gaius Julius Caesar and his sisters Julia Major and Julia Minor ("Julia the elder" and "Julia the younger").