The system of Roman names was very unusual in the ancient world. Names in most other ancient Indo-Euopean cultures did not include an inherited name that indicated lineage within a clan, as did the Roman nomen  . Starting from relatively simple beginnings, as time progressed, Roman names became longer and more complex, including more information about the person named. A foreigner becoming a Roman citizen took a new Roman name as a mark of citizenship.
Typical Roman names of the late Republic had three parts (the "tria nomina"). Example: Gaius Iulius Caesar where:
- Gaius is a praenomen ("given name", plural praenomina),
- Iulius is a nomen ("gens or clan name", plural nomina), and
- Caesar is a cognomen ("family name within a gens", plural cognomina).
Some names had no cognomen, but in other cases a second cognomen, (called an agnomen), was added. Female names could follow similar conventions, with a few differences. Additional elements such as tribal affiliation and "filiation" (parentage), were also sometimes used.
Early social organization in central Italy was centered around the gens, (clan), an "aristocratic lineage or group of lineages and some of their lesser followers and dependents". Inscriptions from the 7th century BCE show names consisting by that date of praenomen (identifies the individual) and nomen (identifies the gens). 
Later, an additional element, the cognomen, was added by aristocrats desiring to connect themselves with the great deeds of specific direct ancestors. Still, some "families never had a cognomen" 
In some cases, "[t]he singular fame of a particular cognomen might allow it to stand for the associated gentilicium [i.e., nomen plus cognomen] in binominal address..." as for example when M. Vipsanius Agrippa is named "M. Agrippa" on the Pantheon (see on picture).
Roman women normally had (or used) only their nomen, but there is ample evidence that many had praenomen and cognomen as well. Praenomen was an attribute of high priestess, such as Vestals, and married women of the highest classes. Cognomina, especially from the late republic, became quite frequent and usually inherited by women, too.
Elements of a name
(Praenomen, plural: praenomina) This form of "first" name was relatively unimportant, and was rarely used on its own outside of the family. There are relatively few praenomina that were commonly used in the Republican era of Rome. Read more about praenomina.
(Nomen plural: nomina) The second name or nomen is the name of the gens (clan) in masculine form; the Latin word "gens" is feminine, so the name appears as feminine in our lists. Read more about nomina.
(Cognomen, plural: cognomina) The third name or cognomen started to be a nickname or personal name that distinguished individuals within the same gens (the cognomen does not appear in official documents until around 100 BCE). During the Roman Republic, the cognomen is inherited from father to son, serving to distinguish a family within a gens. Often the cognomen was based on some physical or personality trait. Read more about cognomina.
Under some circumstances Romans were given an additional cognomen, called an agnomen. These were the exception to the general rule that cognomina were not complimentary.
Read more about agnomina.
Originally, the praenomen and nomen constituted a Roman's full name and were followed by the so-called filiation (a patronymic or indication of paternity) . The filiation (patronymicus) consisted of the Latin word for "son," filius (abbreviated by the letter f.), preceded by the abbreviation of the father's praenomen, which was understood in the genitive case. Hence, a Roman might have been known as
M. Antonius M. f. (=Marci filius), that is, Marcus Antonius, the son of Marcus.
Additionally it could also indicate the grandfather with the word "grandson," nepos (abbreviated by the letter n.).
A tribe was not an indication of common ancestry; the tribes were distributed geographically and a man belonged to the tribe in which his main residence was located. The tribe was an essential part of citizenship, since voting was often carried out by tribe. By the Middle Republic the abbreviation for tribe in which the person was enrolled was added to the person's name. Read more about tribes.
Marcus Aurelius Marci f. Quinti n. tribu Galeria Antoninus Pius.
- praenomen: Marcus
- nomen: Aurelius (he belongs to gens Aurelia, the Aurelii in plural)
- patronymicus: Marci f. (son of Marcus)
- grandparent: Quinti n. (grandson of Quintus)
- tribe: tribu Galeria (a tribe from the region of Caesaraugusta in Hispania)
- cognomen: Antoninus (family of the Antonini)
- agnomen: Pius (probably because of his piety...rarely inherited))
The Pantheon inscription reads in full M. AGRIPPA L. F. COS. TERTIVM FECIT, that is, M. Agrippa, son of Lucius, consul for the third time made (this).
- praenomen: M(arcus)
- cognomen: AGRIPPA
- patronymicus: L(ucii) F(ilius)
In everyday use, people are referred to by either a combination of the praenomen and nomen, or even more usually by just their cognomen.
- "Marcus Livius Drusus" would either be just "Drusus" or "Marcus Livius."
- "Fausta Cornelia Sulla" would be just "Cornelia" (See using Roman names for more on this topic.)
At the time of adoption, the adopted person assumed the adoptive father's full name, and the filiation was changed to refer to the adoptive father. The adoptive son's nomen of birth was appended in adjectival form as an adoptive cognomen, with the ending "-anus". As an example, when L. Aemilius L. f. Paulus was adopted by P. Cornelius Scipio Africanus he used the name P. Cornelius P. f. Scipio Aemelianus.
Twins were favoured in the Roman world. One of the twins might be named Geminus, Gemellus, Consors. The dictator Sulla gave the praenomina Faustus and Fausta to his twins.
- ↑ 1.1 1.2 1.3 1.4 Salway, B. (1994), "What's in a name? A Survey of Roman Onomastic Practice from 700 B.C. to A. D. 700", The Journal of Roman Studies, vol. 84, pp. 124-145 (Retrieve from JSTOR)
- ↑ 2.1 2.2 2.3 Boatwright, M., Gargola, D., Talbert, R. (2004), "The Romans From Village to Empire", Oxford University Press.
- ↑ Kajava, Mika "Roman Female Praenomina:studies in the nomenclature of Roman women" (ISBN 9519690212
- ↑ Dasen, Veronique. "Multiple Births in Graeco-Roman Antiquity", Oxford Journal of Archaeology, Volume 16, Number 1, March 1997 , pp. 49-63(15)
Personal Names in the Roman World
Roman Female Praenomina: Studies in the Nomenclature of Roman Women