from The American Heritage® Dictionary of the English Language, 4th Edition
- adj. Warm and extremely humid.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. humid, or hot and humid.
from the GNU version of the Collaborative International Dictionary of English
- adj. Moist; damp; moldy.
- adj. Warm, damp, and windless; uncomfortably hot and humid; sultry.
from The Century Dictionary and Cyclopedia
- Containing moisture in suspension; damp and close; warm and humid: as, muggy air.
- Moist; damp; moldy.
- Also muggish.
- n. A half-intoxicated person.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- adj. hot or warm and humid
Probably from Middle English mugen, to drizzle; akin to Old Norse mugga, a drizzle.(American Heritage® Dictionary of the English Language, Fourth Edition)
From Old Norse mugga ("drizzle, mist"). (Wiktionary)