Antoniniana seem to have dispensed with praenomina altogether, and by the end of the western empire, only the oldest Roman families continued to use them. Nomen The nomen gentilicium, or "gentile name", designated a Roman citizen as a member of a gens. A gens, which may be translated as "race", "family", or "clan", constituted an extended Roman family, all of whom shared the same nomen, and claimed descent from a common ancestor. Particularly in the early Republic, the gens functioned as a state within the state, observing its own sacred rites, and establishing private laws, which were binding on its members, although not on the community as a whole. Cognomen The cognomen, the third element of the tria nomina, began as an additional personal name. It was not unique to Rome, but Rome was where the cognomen flourished, as the development of the gens and the gradual decline of the praenomen as a useful means of distinguishing between individuals made the cognomen a useful means of identifying both individuals and whole branches of Rome's leading families. In the early years of the Republic, some aristocratic Romans had as many as three cognomina, some of which were hereditary, while others were personal. Like the nomen, cognomina could arise from any number of factors: personal characteristics, habits, occupations, places of origin, heroic exploits, and so forth. One class of cognomina consisted largely of archaic praenomina that were seldom used by the later Republic, although as cognomina these names persisted throughout Imperial times. Many cognomina had unusual terminations for Latin names, ending in -a, -o, or -io, and their meanings were frequently obscure, even in antiquity; this seems to emphasize the manner in which many cognomina originally arose from nicknames. The -ius termination typical of Latin nomina was generally not used for cognomina until the fourth century AD, making it easier to distinguish between nomina and cognomina until the final centuries of the western empire. Unlike the nomen, which was passed down unchanged from father to son, cognomina could appear and disappear almost at will. They were not normally chosen by the persons who bore them, but were earned or bestowed by others, which may account for the wide variety of unflattering names that were used as cognomina. Doubtless some cognomina were used ironically, while others continued in use largely because, whatever their origin, they were useful for distinguishing among individuals and between