A "cognomen" is a type of surname used in ancient Rome, typically indicating a family or clan name. It was the third name in the traditional Roman naming convention, which included the praenomen (given name) and the nomen (family name). Cognomina often described personal characteristics, occupations, or notable achievements of ancestors. In modern usage, the term can refer to any nickname or additional name that a person might adopt. While not commonly used today, cognomina played a significant role in Roman society, helping to distinguish individuals within larger family groups and reflecting their heritage.