agnomen

[ag-noh-muh n] /ægˈnoʊ mən/
noun, plural agnomina
[ag-nom-uh-nuh] /ægˈnɒm ə nə/ (Show IPA)
1.
an additional, fourth name given to a person by the ancient Romans in allusion to some achievement or other circumstance, as “Africanus” in “Publius Cornelius Scipio Africanus.”.
Compare cognomen (def 3).
2.
a nickname.
Origin
1745-55; < Late Latin, equivalent to ad- ad- + nōmen name, with alteration to ag- through influence of agnōscere; see agnize
Related forms
agnominal
[ag-nom-uh-nl] /ægˈnɒm ə nl/ (Show IPA),
adjective
British Dictionary definitions for agnomen

agnomen

/æɡˈnəʊmɛn/
noun (pl) -nomina (-ˈnɒmɪnə)
1.
the fourth name or second cognomen occasionally acquired by an ancient Roman See also cognomen, nomen, praenomen
2.
another word for nickname
Derived Forms
agnominal (æɡˈnɒmɪnəl) adjective
Word Origin
C18: from Late Latin, from ad- in addition to + nōmen name