1. Weight in tons, esp. of cargo or capacity of a ship, etc.
   "The ship's tonnage determined how much cargo it could carry";
   - tunnage [rare]
    
2. A duty imposed on ships based on the tonnage of the ship
   "The port authority collected tonnage duty from all vessels entering the harbour";
   - tunnage [rare], tonnage duty

Derived forms: tonnages

Type of: duty, tariff

Encyclopedia: Tonnage