Overview

Romans had a system of tria nomina (three names) for citizens.

The praenomen	personal name
The nomen	family name
The cognomen	name designating family branch

The plural form of a nomen can be used to refer to a whole family.

The praenomina can be shortened to just the first letter or two:

Letter(s)	Name
A.	Aulus
App.	Appius
C. / G.	Gaius
Cn./ Gn.	Gnaeus
D.	Decimus
L.	Lucius
M.	Marcus
M'.	Manius
P.	Pulius
Q.	Quintus
Ser.	Servius
Sex.	Sextus
Sp.	Spurius
T.	Titus
Ti.	Tiberius

Note that several of these (Decimus, Quintus, Sextus) come from numbers. These may originally have designated simply the birth order of a son.

Feminine forms of these names ending in '-a' are also available. Women were called by the feminine form of their father's cognomen. Further detail is added by using the genitive of a woman's father or husband's cognomen.

Names in general decline like any other noun.