from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A family name; a surname.
- n. The third and usually last name of a citizen of ancient Rome, as Caesar in Gaius Julius Caesar.
- n. A name, especially a descriptive nickname or epithet acquired through usage over a period of time.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. surname
- n. the third part of the name of a citizen of ancient Rome
- n. a nickname or epithet by which someone is identified; a byname; a moniker or sobriquet
from the GNU version of the Collaborative International Dictionary of English
- n. The last of the three names of a person among the ancient Romans, denoting his house or family.
- n. A surname.
from The Century Dictionary and Cyclopedia
- n. A surname; a distinguishing name; specifically, the last of the three names by which a Roman of good family was known, indicating the house to which he belonged. See name.
- n. Loosely, a name, whether a given name, surname, or distinguishing epithet.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a familiar name for a person (often a shortened version of a person's given name)
- n. the name used to identify the members of a family (as distinguished from each member's given name)
Latin cognōmen : co-, con-, co- (influenced by cognōscere, to know) + nōmen, name; see nŏ̄-men- in Indo-European roots.(American Heritage® Dictionary of the English Language, Fourth Edition)
From Latin co- ("together, with") + nōmen ("name"). (Wiktionary)