The nomen identified all free Roman citizens as members of individual gentes, originally families sharing a single nomen and claiming descent from a common ancestor.
Over centuries, a gens could expand from a single family to a large clan, potentially including hundreds or even thousands of members.
No Roman gentes began with "X", and the letters "Y" and "Z" occurred only in names borrowed from Greek.
Nomina are given in the masculine form—the form borne by all male members of a gens.
Those nomina representing gentes for which separate articles exist are linked to those articles; those belonging to only one or two individuals, or known from only a few inscriptions, are not usually linked, but may be cited to the literary sources or inscriptions in which they are attested.