What does cognomen mean?
Cognomen refers, in its broadest modern sense, to a person's surname or family name — the name inherited from one's family rather than given individually. Its most precise and historically rich meaning comes from ancient Rome, where every male citizen bore a three-part name: the praenomen (a personal first name), the nomen gentilicium (the clan name), and the cognomen, which identified a specific branch of that clan and often became hereditary. Famous examples survive in history: Caesar was the cognomen of one branch of the Julii, and Cicero's own cognomen may have derived from an ancestor associated with chickpeas ('cicer'). A related term, agnomen, was sometimes awarded later as an honorific title for military triumphs or other distinctions, as with Scipio Africanus. By extension, English also uses cognomen loosely for any nickname or distinguishing epithet. Today the word appears chiefly in classical scholarship, legal writing, and discussions of names, lending a formal, learned tone wherever it occurs.
nounA cognomen is a surname or family name, or, in ancient Rome, the third name of a Roman citizen that distinguished a family line within a clan (gens). It can also refer more generally to any nickname or distinguishing epithet.
- A surname or family name.
- (Ancient Rome) The third element of a Roman citizen's full name, identifying the family branch within a clan (gens).
- A nickname or distinguishing descriptive name.
"The Roman general Scipio Africanus earned his cognomen after his victory over Carthage."
""What's your cognomen?" she asked, filling out the genealogy chart — he answered with the family name his grandfather had brought from Naples."
"The emperor Vespasian bore the Flavian gens name and took the cognomen Vespasianus, which his sons inherited along with the throne."
Both plurals are accepted; 'cognomina' is preferred in classical scholarship, while 'cognomens' is common in general English usage.
"The inscription lists the cognomina of several prominent families buried at the site."
Julius Caesar wasn't just a name — 'Caesar' was the cognomen of one family branch of the Julian clan, and it stuck so hard we still call emperors by it.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of cognomen
Cognomen comes directly from Latin, where it literally meant 'name known together with' another — formed from co- ('with') plus nomen ('name'), from the Proto-Indo-European root *ǵneh₃- ('to know'), the same root that gives English 'know', 'cognition', and 'recognize'. In classical Latin it denoted the third element of a Roman citizen's formal name. English borrowed the word in the early seventeenth century, retaining both its technical Roman sense and, later, a broader sense of 'surname' or distinguishing nickname.
Related word forms
How cognomen is actually used
Formal and somewhat scholarly in register; most common in historical, classical, and onomastic contexts. In everyday speech 'surname' or 'last name' has almost entirely displaced this sense. The Latin plural is 'cognomina'.
Easily confused with cognomen
An agnomen was an additional honorary name added to a Roman's full name later in life, whereas the cognomen was the standard third name identifying a branch of the family.
In Roman naming, the nomen was the second name indicating the clan (gens), while the cognomen came third and distinguished the particular family within it.