postage
n. uncountable B1 Intermediate US //ˈpoʊstədʒ// UK //pˈəʊstɪdʒ// postage
n. the money you pay to send a letter or package by mail. It also refers to the stamps or marks put on the mail to show you have paid.
n. the charge or fee for sending an item through a postal system. Refers to both the cost incurred and the physical stamps or digital markings that signify payment.
How much is the postage for this heavy box?
The online store offers free shipping, but customers must pay for return postage if they change their minds.
International postage rates vary significantly depending on the destination country and the weight of the parcel being dispatched.
From post + -age.
Usage
Uncountable when referring to the cost or the system of payment; occasionally used with 'the' to refer to a specific fee.