A small wheel or roller, specifically the wheel of a gun carriage. • The ball on top of a flagpole. • On a wooden mast, a circular disc (or sometimes a rectangle) of wood near or at the top of the mast, usually with holes or sheaves to reeve signal halyards; also a temporary or emergency place for a lookout. "Main" refers to the mainmast, whereas a truck on another mast may be called (on the mizzenmast, for example) "mizzen-truck". • A heavier motor vehicle designed to carry goods or to pull a semi-trailer designed to carry goods; (in Malaysia/Singapore) a such vehicle with a closed or covered carriage. • A railroad car, chiefly one designed to carry goods. • Any smaller wagon or cart or vehicle of various designs, pushed or pulled by hand or (obsolete) pulled by an animal, used to move and sometimes lift goods, like those in hotels for moving luggage or in libraries for moving books. • Abbreviation of railroad truck or wheel truck; a pivoting frame, one attached to the bottom of the bed of a railway car at each end, that rests on the axle and which swivels to allow the axle (at each end of which is a solid wheel) to turn with curves in the track. • The part of a skateboard or roller skate that joins the wheels to the deck, consisting of a hanger, baseplate, kingpin, and bushings, and sometimes mounted with a riser in between. • A platform with wheels or casters. • Dirt or other messiness.