from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A sudden, violent downdraft of air over a small area. Microbursts are difficult to detect and predict with standard weather instruments and are especially hazardous to airplanes during landing or takeoff.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A strong downdraft, of less than 2.5 miles in diameter, that can cause damaging winds.
micro- + burst (Wiktionary)