tank⋅age    /ˈtæŋkɪdʒ/ [tang-kij] ânoun 1. the capacity of a tank or tanks. 2. the act or process of storing liquid in a tank. 3. the fee charged for such storage. 4. the residue from tanks in which carcasses and other offal have been steamed and the fat has been rendered, used as a fertilizer.