This word was originally used in defining certain conditions in ocean freight. The term, however, has been carried over into rail car and truck freight lingo. Originally, it meant freight that was paid to guarantee certain storage space in a vessel but was not all used by the shipper. Inasmuch as the shipper had guaranteed to use the space but had not used it, he must pay for it anyway. In carload and truckload shipments dead freight refers to the difference between the actual weight shipped and the lowest minimum weight chargeable to obtain the lowest freight cost.