Was taken from Latin, being the agent noun of

Nomenclature

The term "tractor" (US and Canada) or "tractor unit" (UK) is also applied to:

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  Road tractors, tractor units or traction heads, familiar as the front end of an articulated lorry / semi-trailer truck. They are heavy-duty vehicles with large engines and several axles.
  
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    The majority of these tractors are designed to pull long semi-trailers, most often to transport freight over a significant distance, and is connected to the trailer with a fifth wheel coupling. In England, this type of "tractor" is often called an "artic cab" (short for "articulated" cab).
    
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    A minority is the ballast tractor, whose load is hauled from a drawbar.
    
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  Pushback tractors are used on airports to move aircraft on the ground, most commonly pushing aircraft away from their parking stands.
  
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  Locomotive tractors (engines) or rail car movers – the amalgamation of machines, electrical generators, controls and devices that comprise the traction component of railway vehicles
  
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  Artillery tractors – vehicles used to tow artillery pieces of varying weights.
  
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  NASA and other space agencies use very large tractors to move large launch vehicles and Space Shuttles between their hangars and launch pads.
  
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  A pipe-tractor is a device used for conveying advanced instruments into pipes for measurement and data logging, and the purging of well holes, sewer pipes and other inaccessible tubes.