Tunnage is typically a term used to describe the capacity of a ship's cargo hold or the weight of a ship's cargo. However, there are several synonyms for the word tunnage. The first word for tunnage is "tonnage," which is a similar term that also describes a ship's carrying capacity. Another synonym is "cargo capacity," which emphasizes the amount of cargo that a ship can carry and transport. "Payload" is another synonym that highlights the weight or amount of cargo that can be carried. Lastly, "carrying capacity" is a more general term that applies to any type of transportation and refers to the maximum weight or volume that can be carried safely and efficiently.