Agnomen - a cognomen (surname) conferred by the act of adoption. The adopted Roman took the prenomen and the cognomen (surname) of the adopting party, keeping only the name of his own family. Publius Cornelius Scipio, for example, being adopted by Quintus Caecilius Metellus, called himself Quintus Metellus Scipio. He kept only his original cognomen, the family name he derived from his father, as his agnomen.