1. a narrow band of strong, fast-moving winds in the upper atmosphere, typically at the boundary between warm and cold air masses
Usage: meteorology; often capitalized when referring to a specific jetstream (e.g., the polar jetstream)

Examples

• The jetstream influences weather patterns across North America.
• Pilots often take advantage of the jetstream to reduce flight times on eastbound routes.
• The polar jetstream dipped southward, bringing cold air to the region.
• Climate scientists study how the jetstream is shifting due to global warming.
• The jetstream can reach speeds of over 200 miles per hour.