cognomen

UK: /kɒɡˈnəʊmɛn/ US: (kog nō′mən)

Inflections of 'cognomen' (n):

cognomens

npl

cognomina

npl

WordReference Random House Unabridged Dictionary of American English © 2025

cog•no•men  (kog nō′mən), n., pl. -no•mens, -nom•i•na 

(-nom′ə nə). 
1. a surname.
2. any name, esp. a nickname.
3. Ancient History, Antiquity the third and commonly the last name of a citizen of ancient Rome, indicating the person's house or family, as "Caesar'' in "Gaius Julius Caesar.'' Cf. agnomen (def. 1).

• Latin, equivalent. to co- co- + nōmen name, with -g- on model of nōscī: cognōscī; see cognition
• 1800–10;

cog•nom•i•nal  (kog nom′ə nəl, -nō′mə-), adj.  cog•nom′i•nal•ly, adv. 

Collins Concise English Dictionary © HarperCollins Publishers::

cognomen / kɒɡˈnəʊmɛn/ noun ( -nomens, -nomina / -ˈnɒmɪnə -ˈnəʊ-/)

1. (originally) an ancient Roman's third name or nickname, which later became the family name

Etymology: 19th Century: from Latin: additional name, from co- together + nōmen name; influenced in form by cognōscere to learn

cognominal / kɒɡˈnɒmɪn^əl -ˈnəʊ-/ adjective