Summary of Name Structure
The typical Roman had three names: the praenōmen (first name), the nōmen (gēns name), and the cōgnōmen (family name).
- Mārcus Tullius Cicerō =
- Mārcus (what’s up, Marcus?) +
- Tullius (the time-honored descendants of Servius Tullius, 6th kind of Rome)
- Cicero (the Cicero family, descended from some particular Tullian who earned the nickname ‘chickpea’)
A gēns is much larger than a family, and a Roman was more formally and less intimately attached to the name. ‘Mārcus Tullius Cicerō‘ may be compared to todays ‘John Proper III, descendant of James Black, Duke of York.’
- On the day-to-day, he was just Mārcus Cicerō
- When two members of the same family are mentioned together, the cōgnōmen is plural: Pūblius et Servius Sullae
What About Women?
No first names–no praenōmina, and no family names–no cōgnōmina.
- Cicero’s daughter was Tullia
- Further daughters would have been Tullia secunda, Tullia tertia, etc.
The Essential AG: 108, 108b
Famous Phrase: nōmen est ōmen : the name is a sign
[tied with nominative determinism–the outlook that given names inform what we become and how we develop]
Latin for Addicts 
One thing fronm your post above struck me as an oversimplification and another as an inaccuracy:
1) “The typical Roman had three names” — Was the three-part name (which is not the same as having three names) as widespread among men of low birth and social ranking as it was among those of high birth and/or social ranking? I don’t know, but I doubt it. It seems to me that records about common folks often mention people with a two-name part. We also do know that some well-known political figures, such as Marcus Antonius, only wore a two-part name. It may have been that a man who did not like his cognomen could choose not to use it. Again, I don’t know. In any case, if Marcus Antonius had a cognomen that he didn’t like, I am fairly certain that Cicero would have use it to address him during their feud or mention it in one of his many letters, yet I have never read or heard anything about Marcus Antonius having a cognomen.
2) “No cognomina” for women — This very partial list suggests that the use of a cognomen was not unheard of for women, at least those belonging to high society: http://en.wikipedia.org/wiki/List_of_Roman_women.
I’d struggle to find you precise figures for our battle over the designation ‘typical,’ but I don’t buy into the idea that the ‘Roman’ everyman–slaves, freed slaves, and resident aliens, were properly ‘Roman.’ When a Roman said ‘I am a Roman’ he meant ‘civis Romae,’ a more selective group.
Marc’s father had the cognomen ‘Creticus,’ so I’m surprised that Cicero never uses it in the P’s. It’s apparently a great pun: http://en.wikipedia.org/wiki/Marcus_Antonius_Creticus
That said, I can see why Marc chose not to adopt his father’s nickname.
I’m stumped on the apparently cognomen for someone like Domitia Longina. My only guess is that she’s called that to differentiate her from his sister, according to custom established by this or that author, who first called her that, rather than Domitia Prima.
Thanks for the challenge! Let me know if you have further thoughts on any of this, or a satisfying solution to ?#2 VVVV
While I enjoy reading on Ancient Rome and I know more about it than most people, I am no specialist. Therefore my post wasn’t meant as a challenge, but merely an expression of my surprise. Anyway. There is much to be said about the Romans, being so pragmatic, using such a weird name-giving system.
I’m far too young to be a specialist, and that comment made my day. Indeed, Roman names are an odd bird. I think they persisted because they were too ‘patriotic’ to receive revision. In the same way the eliminating the American penny is hampered by the dear, dear image of Lincoln, the elimination of this or that āgnōmem is hampered by the dear, dear memory of some imperātor’s conquest of Gual.