a motor vehicle used to pull heavy loads, esp farm machinery such as a plough or harvester. It usually has two large rear wheels with deeply treaded tyres
2.
a short motor vehicle with a powerful engine and a driver's cab, used to pull a trailer, as in an articulated lorry
3.
an aircraft with its propeller or propellers mounted in front of the engine
[C18: from Late Latin: one who pulls, from trahere to drag]
1856, "something that pulls," earlier used of a quack device consisting of two metal rods which were supposed to relieve rheumatism (1798, in full Perkins's metallic tractor), from M.L. tractor, from stem of L. trahere "to pull, draw" (see tract (1)). Sense of "an engine or
vehicle for pulling wagons or plows" is first recorded 1901, from earlier traction engine (1859). The meaning "powerful truck for pulling a freight trailer" is first found 1926; tractor-trailer is attested from 1949.