the GNU version of the Collaborative International Dictionary of English
n. See tonnage.
The Century Dictionary and Cyclopedia
n. A tax or duty of so much per tun formerly imposed in England upon all imported wines. Sometimes spelled tonnage, and used chiefly in the phrase tunnage (or tonnage) and poundage. See poundage, 1.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. a tax imposed on ships that enter the US; based on the tonnage of the ship
Word Usage
"This measure of “tunnage” as units of volume should not be confused with other measures of weight that developed later, such as “displacement tons.”"