Teamsters' rigs refer to the semi-trucks and trailers that are driven by members of the International Brotherhood of Teamsters. The term 'Teamsters' rigs' is often used to describe the large, powerful vehicles that are used to transport goods across the country. The five-letter solution for this crossword is SEMIS, which is short for semi-trailers. Semi-trailers are large, box-like trailers that are attached to a tractor unit, usually a semi-truck, and are used to transport goods over long distances.