Noun
The word is derived from cognomen
But as Roman institutions vanished, and the distinction between nomen and cognomen ceased to have any practical importance, so the complex system of cognomina that developed under the later empire faded away. Source: Internet
By the sixth century, traditional Roman cognomina were frequently prefixed by a series of names with Christian religious significance. Source: Internet
Even then, not all Roman citizens bore cognomina, and until the end of the Republic the cognomen was regarded as somewhat less than an official name. Source: Internet
However, it was also common to identify sisters using a variety of names, some of which could be used as either praenomina or cognomina. Source: Internet
Although these names had existed throughout Roman history, it was only in this late period that they were distinguished from other cognomina. Source: Internet
As a result, the cognomina adopted by these citizens, often including their original non-Latin names, became the most important part of their nomenclature. Source: Internet