Les '''noms romains''' se particularisent par l'usage des ''tria nomina'' (trois noms, système d'origine étrusque), en usage surtout chez les patriciens puis chez les plébéiens, au fur et à mesure que, sous la République romaine, ils acquièrent des droits. L'onomastique romaine (science des noms propres) se base sur plusieurs sources : l'étude des pierres tombales, les sources littéraires, enfin l'ensemble de l'épigraphie.

==Noms romains masculins==
=== Principe des ''Tria nomina''===
Le nom complet, pour les citoyens romains, se compose :
*du ''prænomen'' — notre ''prénom'' — qui s'abrège dans les textes s'il est suivi du ''nomen'' (voir les prénoms romains).
*du ''nomen'' (pluriel ''nomina''), qui se termine en généralement en -us/ius, qui est le '''gentilice''' (nom de famille) de la ''gens'' (prononcer ''gens'', groupement social de la taille d’un clan) — on pourrait dire le patronyme.
*du ''cognomen'' — nous dirions surnom — tout d'abord personnel, il finit par distinguer une branche de la ''gens''. Cicéron est un surnom, ''cicero'', qui vient de ''cicer'', « pois chiche » (''un membre de la famille avait une verrue de la taille d'un pois chiche''). La branche paternelle de Néron était surnommée ''Ahenobarbus'', ce qui signifie « (à la) barbe d'airain » (c'est-à-dire rousse). Certains citoyens pouvaient changer de cognomen au cours de leur vie.
* normalement, on indique aussi le nom du ''paterfamilias'', au génitif.

L'histoire a traditionnellement retenu les seuls ''nomen'' et ''cognomen'' voire uniquement le ''cognomen'' des Romains célèbres, excepté pour les Claude et Néron s'appelaient tous ''Tiberius Claudius Nero''.

===Le cognomen===
Un général vainqueur recevait un nom supplémentaire, tiré de la peuplade vaincue (Carthaginois, l'empereur ''Claude le Gothique'', vainqueur des Goths, ''Germanicus'', vainqueur des Germains, etc.).

Les adoptés changeaient leur ''nomen'' et ''cognomen'' pour ceux de l'adoptant et adjoignaient un second ''cognomen'' en ''-anus'' rappelant leur ''gens'' d'origine. Les ''cognomina'' pouvaient s'additionner sans limite de nombre. À l'origine, celui que nous connaissons comme Auguste se nommait ''Caius Octavius'' - francisé en Octave - puis, après son adoption par Jules César, il devint ''Caius Iulius Caesar'' '''''Octavianus''''' — il est parfois appelé en français Octavien — et après son accession au principat, il prit en troisième ''cognomen'' « ''augustus'' » soit ''Caius Iulius Caesar Octavianus Augustus''.

Suivant cet exemple, chaque empereur, lors de son accession au trône, ajoutait César ou Auguste à ses noms. Cet usage a fini par transformer ces noms en titres, synonymes d'empereurs.

==Noms romains féminins==
Les femmes romaines sont désignées uniquement (sur les tombes et dans les œuvres littéraires et historiques) par une forme féminisée du ''nomen'' de la ''gens'' : Claudius → Claudia, Cornelius → Cornelia, Tullius → Tullia, etc. Chacune était ensuite distinguée de ses sœurs par un qualificatif, par exemple : ''maior'' (l'ancienne) / ''minor'' (la jeune).

By the Republican era and throughout the Imperial era, a '''name''' in '''ancient Rome''' for a male citizen consisted of three parts (''tria nomina''): '''praenomen''' (given name), '''nomen (gentile)''' (name of the ''gens'' or clan) and '''cognomen''' (name of a family line within the ''gens'').  The ''nomen'', and later, ''cognomen'' were virtually always hereditary. Women usually did not have the ''praenomen'' and ''agnomen'' (nickname), which were normally distinct and not necessarily hereditary (unless the parents chose to).

==History==

In the early regal period of Rome, it appears that people were at first referred to by one name (e.g., ''pater familias''' name, which became a fixed and inherited ''nomen''.  

This binomial nomenclature was unique among Indo-European languages of that era. Also, the core part of the name (''nomen'') was the inherited gens name, not the given name (''praenomen'').  This is probably why so few different ''praenomina'' were used.

Later in the Republic a ''cognomen'' was added to distinguish families within a gens, as the importance of the gens grew and the size of voting tribes required this differentiation. Thus patricians (nobility) commonly had three names (''Tria Nomina'').  Although this system dates to the later 5th century BC, it was slow to take root, as it does not appear in official documents until the late 2nd century BC and was not common until the time of Sulla, right before the Empire. It was adopted even more slowly by non-patricians; the first examples of cognomina for plebeians date to c. 125 BC and it was not popular for another century. 

In the Roman language, culture and names were gradually replaced by Greek ones.

== Praenomen ==

The ''praenomen'', equivalent to ''pater familias'' naming male infants after himself). There was, however, a very limited selection of ''praenomina'', such as Gaius, Gnaeus, Marcus, Quintus, Publius, Tiberius, and Titus. As a result, men from a given family often have identical names for generations. It was therefore necessary to use other names (''cognomen'' and later, ''agnomen'') to distinguish between individuals. Only intimates would use the praenomen.

== Nomen ==

The second name, or ''nomen gentile'' (usually simply ''nomen''), rarely ''gentilicium'', is the name of the ''Etruscan families, while others were from local tribes or from major geographical features, such as rivers. Well-known nomina include many of the familiar names of ancient Rome, such as Claudius, Cornelius, Domitius, Julius, Junius, Pompeius, Antonius, and Valerius.

== Cognomen ==<!-- This section is linked from Blackadder -->

The third name, or ''cognomen'', began as a nickname or personal name that distinguished individuals with the same names. ''Cognomina'' do not appear in official documents until around 100 BC. Often the cognomen was chosen based on some physical or personality trait, sometimes with ironic results: balding, and Tacitus's cognomen meant ''silent'', while he was a well-known orator. However, since the Republican era, the cognomen was no longer a nickname, becoming inherited from father to son, serving to distinguish a family within a gens.

=== ''Nomen''-derived names ===
Some males had a ''cognomen'' that ends in ''-anus'', which was adapted from and commemorated a ''nomen'', sometimes their maternal family or &ndash; if they were adopted &ndash; their original paternal family. For instance, Vespasian's ''nomen'' (Flavius) came from his father's ''nomen''. His ''cognomen'' (Vespasianus), on the other hand, was derived from his mother's ''nomen'' , Vespasia. Others had cognomina that were derived not from the ''nomen'', but the ''cognomen'' of their mothers' families. For instance, Caracalla's maternal grandfather was Julius Bassianus, but Caracalla's cognomen was not Julianus, but rather Bassianus as well.

When a man was adopted into another family, his would take on his adopted father's names (excluding the ''praenomen''). If he chose to, he could turn his original ''nomen'' into an additional ''cognomen'' that followed his newly gained names.  For example, these adoptees incorporated into their new names their adopted family's ''nomen'' and ''cognomen'', and also kept their birth family's ''nomen'':
* Publius Cornelius Scipio Aemilianus: Publius was adopted into the ''gens'' Cornelii Scipiones, but was born an Aemilius, and
* Mamercus Aemilius Lepidus Livianus: Mamercus was born a Livius, adopted into Aemilii Lepidi. However, not all adoptees chose to identify their birth families. For instance, as an adult, Augustus did not use his cognomen ''Octavianus'', since the ''gens'' Octavii were not nearly as esteemed as the Julii. (''See also'': Adoption in Rome)

== Agnomen ==

After the ''cognomen'' became hereditary and lost its function as a nickname, a second nickname, or ''agnomen'', was appended to the name after birth &ndash; usually not immediately &ndash; to signify some personal characteristic or accomplishment. A common ''agnomen'' was ''Pius'', for someone who displayed virtues like honesty, reverence to the gods, or devotion to family and state. ''Superbus'' ("Haughty") and ''Pulcher'' ("Handsome") were also examples of ''agnomina''.

Unlike the ''nomen'' and ''cognomen'', an ''agnomen'' was usually not inherited unless the son also had the same attribute or did the same deeds. Although some victory ''agnomina'' like ''Augustus'' ("Majestic") and ''Germanicus'' ("the German (Conqueror)") eventually became handed down as additional ''cognomina''. 

Names adapted from ''nomina'' (with the ''-anus'' suffix) are sometimes considered ''agnomina''. Priscian specifically cites Claudianus and Aemilianus as examples.

== Foreign names ==
As Rome conquered territories beyond the Italian peninsula, many foreign names were introduced. Discharged auxiliary soldiers and others gaining Roman Citizenship could, and many did, continue to use at least a portion of their former names. Most were of Greek origin, while others came from regions that were brought under Roman influence. Non-citizen auxiliary soldiers who were granted citizenship often adopted the '''nomen''' of their Emperor, adding their native name as a '''cognomen'''. 

New citizens often also took on the ''nomen'' of the reigning emperor. For instance, after Caracalla ("Marcus Aurelius Septimius Bassianus Antoninus") expanded citizenship to all freedmen in the empire, many of them took on the ''nomen'' Aurelius. (Caracalla's correct ''nomen'' was actually ''Septimius''. ''Aurelius'' was a pretension to Roman nobility.)

== Female names ==

Roman women usually had no ''praenomen'' and were known only by the feminine form of their father's ''nomen'' so that daughters were all named with the same feminine version of the family nomen. If further description was needed, the name was followed by the genitive case of her father's ''cognomen'' or, after marriage, of her husband's. Hence, Cicero speaks of a woman as "Annia P. Anni senatoris filia" (Annia the daughter of P. Annius the senator). By the late Republic, women also adopted the feminine form of their father's ''cognomen'', e.g., Aquilia Severa was the daughter of Aquilius and married a Severus (in her case, both of her names are derived from ''nomina''). Feminized ''cognomen'' was often made a diminutive, e.g. Augustus's wife Livia Drusilla was the daughter of a M. Livius Drusus. 

If only two daughters survived, they could be distinguished as ''major'' and ''minor''. Marcus Antonius's daughters were Antonia major (grandmother of the emperor Nero) and Antonia minor (mother of the emperor Claudius). If a family had more than two daughters, they were distinguished by ordinal numbers: Cornelia Quinta, the fifth daughter of a Cornelius. The epithets of ''major'' and ''minor'' also served to distinguish between daughters and mothers of the same name, e.g., Agrippina the Younger and Julia the Younger, respective daughters of Agrippina the Elder and Julia the Elder.