A cowl unit is a body style of diesel locomotive. The terminology is a North American one, though similar locomotives exist elsewhere. A cowl unit is one with full-width enclosing bodywork, similar to the cab unit style of earlier locomotives, but unlike the cab unit style, the bodywork is merely a casing and is not load-bearing. All the strength is in the locomotive's frame, beneath the floor, rather than the bridge-truss load-bearing carbody of the earlier type.