Cognomen
A Dictionary of Law · Henry Campbell Black · 1891
A Dictionary of Law
In Romanlaw. A man’s family name. The first name (pranomen) was the proper name of the individual; the second (momen) indicated the gens or tribe to which he belonged; while the third (ceynomen) denoted his family or house. in English law.
A surname
A name added to the nomen proper, or name of the individual; a name descriptive of the family. Cognomen majorum est ex sanguine tractum, hoc intrinsecum est; agnomen extrinsecum ab eventu.
6 Coke, 65.
Tho cognomen is derived from the blood of ancestors, und is intrinsic; an agnomen arises from an event, and is extrinsic,