: an instrument used to exert traction on a body part or tissue (as in surgical procedures) <a urethral tractor>
High-power, low-speed traction vehicle. The two main types are wheeled and continuous-track. Most modern tractors are powered by internal-combustion engines running on gasoline or diesel fuel. Tractors are used in agriculture, construction, and road building, for pulling equipment such as plows and cultivators, for pushing implements such as bulldozers and diggers, and for operating stationary devices such as saws and winches. The first tractors grew out of the steam engines used on farms in the late 19th century; in 1892 an Iowa blacksmith, John Froehlich, built the first farm vehicle powered by a gasoline engine. The tractor revolutionized farming, displacing draft animals and many farm workers. By World War I the tractor inspired the tanks built by the British and French.