noun: (informal) Abbreviation of articulated lorry; A semi-trailer truck. [(Britain) A tractor-trailer or big rig, consisting of a semi-trailer and a semitruck pulling it; in American English referred to as semi-trailer truck or 18-wheeler.]
noun: (informal) Abbreviation of articulated bus [A bus fitted with a joint, which is covered by an accordion-shaped weatherproofing, to increase its manoeuvrability.]