What is definition cognomen?

Cognomen is a Latin term that refers to a nickname or surname adopted by ancient Roman families to distinguish themselves from others with the same given name. These surnames were usually descriptive, denoting a physical feature, occupation, or personal characteristic of the individual or their ancestors. For example, the cognomen "Caesar" was adopted by Julius Caesar's family because it referred to his ancestor's curly hair. Cognomen were particularly important in military and political circles as they helped to identify a person's family lineage and also served as a symbol of their achievements and reputation.