from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Informal Mail delivered by a postal system, as distinct from electronic mail.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. Postal mail, especially as compared to email
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. any mail that is physically delivered by the postal service
A retronym emphasizing postal mail's slowness compared to email. (Wiktionary)