Learner's definition of COUPON
1 : a usually small piece of printed paper that lets you get a service or product for free or at a lower price
Bring in this coupon for a free oil change.
I'm always clipping coupons from the newspaper to use at the grocery store.
The coupon is good for one free ice-cream cone.
2 chiefly British : a section of an advertisement that you can cut out and mail to a company in order to request information or to order a product or service