Plain English Meaning

The fast, spiraling column of air that the propeller throws backward over the airplane. Because it twists as it flows back, it pushes on the tail unevenly and tries to swing the nose to one side.

Full Definition

The tube of air accelerated rearward by a propeller. The slipstream rotates around the fuselage in the direction the propeller turns and strikes the vertical tail and other rear surfaces at an angle, producing yawing and other handling effects, especially at high power and low airspeed.

Context Anchor

Seen in climb, takeoff, and slow-flight discussions where high power makes the propeller more noticeable.