In Roman law. A man’s family name. The first name (prcnnomcn) was the proper name of the individual ; the second (nornen) indicated the gens or tribe to which he belonged ; while the third (cognomen) denoted his family or house. In English law . A surname. A name added to the nomcn proper, or name of the individual; a name descriptive of the family. Cognomen majorum est ex sanguine tractum, hoc intrinsecum est; agnomen extrinsecmm ab eventu. 6 Coke, 65. The cognomen is derived from the blood of ancestors, and is intrinsic; an agnomen arises from an event, and is extrinsic.