1. To cast overboard or off: a ship jettisoning wastes; a pilot jettisoning aircraft fuel.
2. Informal. To discard (something) as unwanted or burdensome: jettisoned the whole marketing plan.

1. The act of discarding or casting overboard.
2. Jetsam.

[From Middle English jetteson, a throwing overboard of goods to lighten ship, from Anglo-Norman getteson, from Vulgar Latin *iectātiō, iectātiōn-, from *iectātus, past participle of *iectāre, to throw. See jet².]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.