Agnomen

Optional nickname in the Roman Republic

An agnomen, in the Roman naming convention, was a nickname, just as the cognomen had been initially. However, the cognomina eventually became family names, and so agnomina were needed to distinguish between similarly-named persons. However, as the agnomen was an additional and optional component in a Roman name, not all Romans had an agnomen.

This keyword could refer to multiple things. Here are some suggestions: