tractor-trailer

Truck Truck, n. [L. trochus an iron hoop, Gr. ? a wheel, fr. ? to run. See {Trochee}, and cf. {Truckle}, v. i.] 1. A small wheel, as of a vehicle; specifically (Ord.), a small strong wheel, as of wood or iron, for a gun carriage. [1913 Webster]

2. A low, wheeled vehicle or barrow for carrying goods, stone, and other heavy articles. [1913 Webster]

Goods were conveyed about the town almost exclusively in trucks drawn by dogs. --Macaulay. [1913 Webster]

3. (Railroad Mach.) A swiveling carriage, consisting of a frame with one or more pairs of wheels and the necessary boxes, springs, etc., to carry and guide one end of a locomotive or a car; -- sometimes called bogie in England. Trucks usually have four or six wheels. [1913 Webster]

4. (Naut.) (a) A small wooden cap at the summit of a flagstaff or a masthead, having holes in it for reeving halyards through. (b) A small piece of wood, usually cylindrical or disk-shaped, used for various purposes. [1913 Webster]

5. A freight car. [Eng.] [1913 Webster]

6. A frame on low wheels or rollers; -- used for various purposes, as for a movable support for heavy bodies. [1913 Webster]

7. a motorized vehicle larger than an automobile with a compartment in front for the driver, behind which is a separate compartment for freight; esp. (a) such a vehicle with an inflexible body. (b) A vehicle with a short body and a support for attaching a trailer; -- also called a {tractor[4]}. (c) the combination of tractor and trailer, also called a {tractor-trailer} (a form of articulated vehicle); it is a common form of truck, and is used primarily for hauling freight on a highway. (d) a tractor with more than one trailer attached in a series. In Australia, often referred to as a {road train}. [PJC]