Roman Names: Tria Nomina and Filiation
Modern students are often puzzled by the lengthy and obscure Roman names. How many names does a male Roman need? Why do so many Romans in the same family have identical names?
The names originally weren't so convoluted. In pre-Republican days, back when Rome was still under the control of Etruscan overlords, most male Roman citizens went by a single name. The naming process grew increasingly complicated as time went by. Below, you will find a list of each "stage" in the development of the Roman name, followed by conventions for naming women, and the process of filiation for voting purposes.
Stage I--Name Plus Tribe: In the first historical stage, a child's parents would choose would choose a praenomen (Lat. "pre-name," plural praenomina) for their infant. They would make this decision as part of the lustral day (dies lustricus), when a naming ritual would take place. This rite occurred on the eighth day after a girl's birth or the ninth day after a boy's birth, but the parents would formalize or finalize that choice when the girl was fourteen and about to be married, or when the boy assumed the toga virilis (the adult toga, garb that later Roman sumptuary laws required young Roman men to wear in the forum or on certain formal days).
Romans would use this praenomen combined with the name of a child's tribu, or tribe. English speakers might think of this naming convention as roughly akin to the praenomen being a "first name" given by parents and the tribu indicating a very large, loose ethnic group. It might be roughly comparable to American emigrants using the praenomina as a first name and a large ethnic group like "Scottish" or "Irish" for one's last name.
However, this simple naming convention proved inadequate very quickly. At the time of the Etruscan revolt, only three original tribes existed in Rome society--providing far too few names for keeping accurate records and distinguishing between individuals. By the height of the Republican period, that number had grown to four urban tribes and perhaps a dozen rural tribes, reaching a maximum number of about thirty-five tribes in 242 BCE.
Stage II--Name Plus Gens: To be more specific in identity, it became common to identify oneself by a nomen gentile, a masculinized form of the gens (plural gentes) or extended family that could trace itself back to one of the oldest Roman settlers. English speakers might think of this nomen gentile roughly as something more similar to our "last name," indicating a large, loose family.
However, this two-part naming convention also proved inadequate as time passed. Among the original Roman families who helped overthrow the Etruscans, there were probably about twenty nomina gentiles, or available "last names." It wasn't until later centuries that the number of nomina gentiles increased as the Romans slowly and grudgingly added certain Etruscan tribal names and names of Italian tribes to the official record list--a course conservative Romans were loath to take because the voting system in Republican Rome was based on blocks determined by tribe or family.
As a further complication, the custom gradually developed that the pater familias (oldest male in the family) became responsible for naming newborn infants in his family, not the parents themselves. As this custom changed, it became increasingly common for that pater familias to name newborn males in his family with his own praenomen (especially the oldest child of one of his descendants). It also became common for the pater familias to name non-firstborn sons after a grandfather or uncle. So, in a typical Roman family, multiple men would share an identical name across multiple generations, a source of confusion in social relations and governmental records. To make that problem even worse, only a small number of praenomina existed to choose from in this two-part naming convention--perhaps only a dozen common and fashionable ones originally.
Stage III--Workaround Methods, the Cognomen, and Tria Nomina: Subsequently, to avoid confusion, Romans employed two different strategies to keep names straight.
(1) The first (and more formal and awkward) work-around for clarity's sake was to add a genitive nomen--often a patronymic "son of male X" or a matronymic "son of female Y") in addition to the nomen gentile and praenomen. For instance, if in a conversation the speaker referred to two individuals who shared the praenomen "Flavius," and were both of the extended family or gens "Cassius," it would become confusing to refer to them both as "Flavius Cassius." To distinguish between them, the speaker might refer to one "Flavius Cassius, Filius Julii" (Flavius Cassius, the son of Julius) and to the other as "Flavius Calpurnianus Cassius" (i.e., "Flavius Cassius, the son of Calpurnia," with the Calpurnianus-bit being an adjectival back-formation from the praenomen of his mother, Calpurnia Pollo.)
(2) The second (and more informal) strategy was to distinguish between two similar names by adding an informal nickname. By Republican times in 100 BCE, it became common for Patrician families (but not Plebians) to add a third descriptive name called a cognomen (Lat. "known name," plural cognomina) based on some well-known, distinctive or visible feature. For instance, the cognomen Rufus (Lat. "the red") to a man with red hair or reddish skin, Ahenobarbus (Lat. "dyed red-beard") to a man with thick, fiery facial hair, Scaevola or Sinister (Lat. "left-handed") given to a south-paw. More colorfully, Carnax (Lat. "butcher") might be given as a nickname to a particularly brutal soldier, or Magnus (Lat. "the Great") given to an outstanding general. Sometimes, the cognomen might be ironic or humorous, as in the case of the cognomen Tacitus ("silent") for a famously talkative orator, or Caesar ("curly-haired") for a bald man, or Exiguus (Lat. "shorty") given to a very tall individual. In other cases, the cognomen might refer to a geographic area in Rome, or a man's home-town, or a well-known estate where he lived, and so forth. Others are simply bizarre, such as the cognomen Cicero (from Lat. cicer, "chickpea"). In Republican and early Imperial times, most Patricians would refer to each other informally by cognomina alone.
The combination of praenomen, nomen gentile, and cognomen together is known as the tria nomina, the three names of a male Roman citizen in the Republic.
Stage IV--The Agnomen: By late Imperial times, that convention of the tria nomina also became insufficient for distinguishing citizens. Increasingly, cognomina became hereditary, passed from father to son, and thus divorced from the original physical trait or characteristic they referred to. That change caused even more confusion. At this point, a few select individuals gained the right to add an agnomen (plural agnomina) to their names. No child would be given an agnomen at birth, but rather this title would be appended to a name after earning some special glory or completing some significant accomplishment--e.g., service as a pontifex maximus (high priest), winning an outstanding military victory, and so forth. Examples of such agnomina include Pius (Lat. "devoted"), which might be added to a man who served a term as priest, or Pulcher (Lat. "handsome"), which might be given to a famous athlete. The Roman Senate eagerly proposed new agnomina for victorious generals with the new fourth name coming from the geographic area they conquered. Thus, we find the agnomen Germanicus for those who fought German tribes, Africanus for those who beat Carthaginian armies, and so forth. It might have been something of a status symbol to have multiple names along these lines.
Women's Names: For good or bad, Roman women originally went through a much simpler naming convention--they typically were given a feminine version of their father's name. So, if a father's name was Livius, all his daughters would be named Livia. To keep the girls straight, the parents might distinguish between Livia Maior ("the older Livia girl") and Livia Minor ("the younger Livia girl"). If the family had more than two surviving daughters, the parents might refer to them by number, i.e., Livia Prima (first-born Livia), Livia Secunda (second-born Livia), Livia Tertia, Livia Quarta, Quinta, Sexta, Septima, and so forth. If the daughters had particularly distinctive features, they might be referred to with a descriptive adjective: Livia Exigua (the short Livia), Livia Amanda (the lovable Livia), Livia Superba (the snooty Livia), and so on. In another very common distinction, the parents might add a diminutive-marker to one of the various Livia's names, turning her into something akin to Livellia--a very common practice for the youngest daughter if she were the baby of the family. With a bit more dignity, by the end of the Republic period, many Patrician women also adopted a feminine version of their father's or pater familias' cognomen or nickname--particularly if their father was especially well-known or prestigious. Thus, women from illustrious families might end up with two formal names, while women from lesser-known families would either share a name with all their sisters, but possibly might have a nickname or number to help distinguish them from their siblings.
Filiation: For voting purposes, it was common for men to recite filiation, a combination of name and genealogy, and address. This formula would be a voting Roman's official "full name" for governmental records, roughly akin to a social security number in America. (Incidentally, I suspect that organization-loving Romans would have delighted in the idea of social security numbers if only their numbering system had included a zero.) The formula for filiation would be to list one's personal praenomen, followed by one's nomen gentile, followed by the patronimicus (the praenomina of one's immediate father) followed by the grandfather's praenomina, then the tribal designation, followed by the cognomen (if any), agnomen (if any), and a place of residence. For instance, "Brutus Cassius Sexti filius Bruti nepos tribu Galeria Suetonius Carnax domo Hispania" would mean Brutus of the Cassius family, son of Sextus, grandson of Brutus, of the Galerian tribe, of the Suetonius branch, nicknamed the Butcher, residing in Hispania." Harried scribes might abbreviate that as "B. Cassius S. f. B. n. Gal. t. Suetonius Carnax d. Hispan." to speed up the process as voters lined up and rattled off the filiation while the government workers frantically scribbled down the information.)
In terms of literature, the convention in English is to refer to major Roman poets and orators by their cognomina alone. Thus, Publius Vergilius Maro becomes simply Vergilius (Virgil). Publius Ovidius Naso become simply Ovidius (Ovid). You will find their works commonly alphabetized in English libraries accordingly.