from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A visible trail of streaks of condensed water vapor or ice crystals sometimes forming in the wake of an aircraft. Also called vapor trail.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. An artificial cloud made by the exhaust of jet aircraft or wingtip vortices that precipitate a stream of tiny ice crystals in moist, frigid upper air.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. an artificial cloud created by an aircraft; caused either by condensation due to the reduction in air pressure above the wing surface or by water vapor in the engine exhaust
con(densation) + trail.(American Heritage® Dictionary of the English Language, Fourth Edition)
Blend of condensation and trail (Wiktionary)