The term 'very large truck' can be summarized by the crossword solution of 'SEMI', which is a four letter word. A SEMI-truck, also known as a tractor-trailer, is a large truck used for transporting goods over long distances. It consists of a tractor unit, which is the cab, and one or more trailers. The tractor unit is connected to the trailer by a fifth wheel coupling. SEMI-trucks are commonly used in the transportation industry due to their size and capacity to carry large amounts of cargo.