antitorque rotor

[ an-tee-tawrk, an-tahy- ]
/ ˌæn tiˈtɔrk, ˌæn taɪ- /

noun Aeronautics.

(on certain helicopters) a small rotor on the tail, turning in the vertical plane and providing a thrust whose torque opposes and compensates for the torque of the main rotor.

Origin of antitorque rotor Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019