The crossword solution for the term IT MAY JACKKNIFE is SEMI, which is an abbreviation for SEMI-trailer truck. A SEMI-trailer truck is a large vehicle that consists of a tractor unit and one or more trailers. It is used to transport goods over long distances. The jackknife maneuver is a driving technique used to turn a SEMI-trailer truck in a tight space. It involves the driver turning the tractor unit sharply while the trailer swings out in the opposite direction.