Cognomen

·noun A Surname.

II. Cognomen ·noun The last of the three names of a person among the ancient Romans, denoting his house or family.

cognomen
cognōmen, ĭnis, n. [co-nomen]. I A name added to the nomen (or name of the gens), usu. the third wo...

A New Latin Dictionary by Charlton T. Lewis Ph.D. and Charles Short, LL. D.
cognomen
cōgnōmen inis, n com- + GNA-, a surname, second-name, family-name (added to the name of the gens t...

An Elementary Latin Dictionary