Webster's Revised Unabridged Dictionary · 1913

Tractor screw

Tractor screw

(Aviation) A propeller screw placed in front of the supporting planes of an airplane instead of behind them, so that it exerts a pull instead of a push. Hence, Tractor monoplane, Tractor biplane, etc. This is the most common arrangement for propellers on modern airplanes.

Also: Tractor propeller