cognomen

(kŏg-nōˈmən)

1. a. A family name; a surname.
   b. The third and usually last name of a citizen of ancient Rome, as Caesar in Gaius Julius Caesar.
2. A name, especially a descriptive nickname or epithet acquired through usage over a period of time.

Related Forms:

• cog·nomˈi·nal (-nŏmˈə-nəl) adjective