from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A downward air current that causes an aircraft to lose altitude abruptly. Also called air hole.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. a local region of low atmospheric pressure, or a local downward current; especially one that causes an aircraft to lose height suddenly
from the GNU version of the Collaborative International Dictionary of English
- A local region in the atmosphere having a downward movement and offering less than normal support for the sustaining surfaces of a flying machine, causing an airplane to drop suddenly. Same as air hole.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a local region of low pressure or descending air that causes a plane to lose height suddenly
Sorry, no etymologies found.