tractor

\ \ [17] Tractor is one of a large family of English words that come from tractus, the past participle of Latin trahere ‘pull’ (others include abstract [14], attract, contract, detract [15], distract [14], extract [15], retract, subtract, trace, tract [14], tractable [16], traction [17], trait, treat, treatise, and treaty). Tractor itself was originally used in English for a device, invented by the 18th-century American doctor Elisha Perkins, for ‘pulling’ across the surface of the skin, which was supposed to relieve rheumatic pains. It was not applied to a ‘vehicle for pulling loads’ until the end of the 19th century.

\ \ From Latin trahere itself come English retreat and train; and drag may go back to the same ultimate source.

\ \ Cf.⇒ ABSTRACT, ATTRACT, CONTRACT, DETRACT, DISTRACT, EXTRACT, RETRACT, RETREAT, SUBTRACT, TRACE, TRACT, TRAIN, TRAIT, TREAT, TREATY