surname (n.) Look up surname at Dictionary.com
c.1300, "name, title, or epithet added to a person's name," from sur "above" (from Latin super-; see sur- (1)) + name (n.); modeled on Anglo-French surnoun "surname" (early 14c.), variant of Old French sornom, from sur "over" + nom "name." As "family name" from late 14c.

An Old English word for this was freonama, literally "free name." Meaning "family name" is first found late 14c. Hereditary surnames existed among Norman nobility in England in early 12c., among the common people they began to be used 13c., increasingly frequent until near universal by end of 14c. The process was later in the north of England than the south. The verb is attested from 1510s. Related: Surnamed.