|| A road tractor coupled to a semi-trailer is often called a semi-trailer truck or semi, or in the UK an articulated lorry.
A semi-trailer truck, also known as a semi, tractor-trailer, or (in the United Kingdom and Ireland) articulated truck or articulated lorry, is an articulated vehicle consisting of a towing engine (tractor in the United States, prime mover in Australia or truck in Ireland, the United Kingdom, Canada and New Zealand), and a semi-trailer (plus possible additional trailers) that carries the freight.