from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A name by which one people or social group refers to another and by which the group so named does not refer to itself.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A name given to a group or category of people by a secondary person or persons other than the people it refers to.
exo- (“outside”) + -onym (“name”) (Wiktionary)