noun /ˈkuː.pɒn,ˈkuː.pɑn,ˈkjuː.pɑn/
a) Any interest payment made or due on a bond, debenture or similar (no longer by a physical coupon).
b) A section of a ticket, showing the holder to be entitled to some specified accommodation or service, as to a passage over a designated line of travel, a particular seat in a theater, a discount, etc.
Wikipedia foundation.