The definition of last name is your surname or the name handed down from your parents.
For someone named Jim Smith, Smith is an example of a last name.
(plural last names)
- A surname.
- A last name is so called because it is in English written last, after the given names. However, in many other languages and cultures this name precedes the given name; in these cases, the terms surname or family name are more appropriate.
- attributive form of last name, noun.
- I need last-name information from the database.