sur·name 
(sûrnām′)
(sûrnām′)n.
1. A name shared in common to identify the members of a family, as distinguished from each member's given name. Also called family name, last name.
2. A nickname or epithet added to a person's name.
tr.v. sur·named, sur·nam·ing, sur·names
To give a surname to.
[Middle English, partial translation of Old French surnom : sur-, sur- + nom, name.]