n. pl. cog·no·mens or cog·nom·i·na (-nŏmə-nə)
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.
[Latin cognōmen : co-, con-, co- (influenced by cognōscere, to know) + nōmen, name; see n-men- in the Appendix of Indo-European roots.]
cog·nomi·nal (-nŏmə-nəl) adj.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.