- any of several bands of high-velocity winds moving from west to east around the earth at altitudes from c. 12 to 16 km (c. 8 to 10 mi)
- the stream of exhaust from any reaction enginealso jetstream
- A high-speed, meandering wind current, generally moving from a westerly direction at speeds often exceeding 400 kilometers (250 miles) per hour at altitudes of 10 to 15 kilometers (6 to 9 miles).
- A high-speed stream; a jet.
(plural jet streams)
- (meteorology) any of the high-speed, high-altitude air currents that circle the Earth in a westerly direction