cognomen
/kɒɡˈnɒmɛn/ or /kɔɡˈnɒmɛn/Definitions
1. noun
A person’s surname or family name, especially one that is used to distinguish a person from others with the same given name, or a name that was added to an individual’s nomenclature to signify their status, achievement, or relationship to a particular group or family.
“The Roman poet known by his cognomen ‘Virgil’ is one of the most celebrated poets of ancient Rome.”