from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Informal A photograph of a person's face, especially one made for police files.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A photograph taken of the head and shoulders, often from the front and in profile, usually taken in conjunction with somebody's arrest.
- n. An unflattering photograph of a person's face.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a photograph of someone's face (especially one made for police records)
Compound of mug ("face") + shot ("snapshot"), US. Compare mug ("portrait"). (Wiktionary)