Cognomen

The cognomen was the third name and usually was given later in life as a title of distinction, for example Gaius Julius Caesar, or might refer to some physical characteristic, for example Rufus meant "red-haired". The cognomen might be handed down to a man's children, or it might not.

Women carried, as their legal names, only the feminine form of their father's nomen. For example, all the daughters of all the Julius family were legally named Julia. A woman might also use a form of her father's cognomen and so be known as Julia Caesaria.

A slave freed by his master adopted the master's first two names and added his own slave name as cognomen. For example, Marcus Tullius Tiro was the freed slave secretary of Marcus Tullius Cicero.