tonnage

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The number of tons of water that a ship displaces when afloat.
• noun The capacity of a merchant ship in units of 100 cubic feet.
• noun A duty or charge per ton on cargo, as at a port or canal.
• noun The total shipping of a country or port, figured in tons, with reference to carrying capacity.
• noun Weight measured in tons.

from The Century Dictionary.

• To levy tonnage upon.
• To have capacity or tonnage: followed by an accusative of quantity.
• noun The weight of goods carried in a boat or ship.
• noun The carrying capacity of a ship expressed in cubic tons.
• noun A duty or impost on ships, formerly estimated at so much per ton of freight, but now proportioned to the registered size of the vessels.
• noun The ships of a port or nation collectively estimated by their capacity in tons: as, the tonnage of the United States.

from the GNU version of the Collaborative International Dictionary of English.

• noun The weight of goods carried in a boat or a ship.
• noun The cubical content or burden of a vessel, or vessels, in tons; or, the amount of weight which one or several vessels may carry. See Ton, n. (b).
• noun A duty or impost on vessels, estimated per ton, or, a duty, toll, or rate payable on goods per ton transported on canals.
• noun The whole amount of shipping estimated by tons. See Ton.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The number of tons of water that a floating ship displaces.
• noun The capacity of a ship's hold etc in units of 100 cubic feet.
• noun The number of tons of bombs dropped in a particular region over a particular period of time.
• noun A charge made on each ton of cargo when landed etc.
• noun The total shipping of a fleet or nation.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a tax imposed on ships that enter the US; based on the tonnage of the ship