gift (gift): noun

Something given voluntarily without payment in return, as to show favor toward someone, honor an occasion, or make a gesture of assistance; present.

certificate (ser-tif-i-kit): noun

A document serving as evidence or as written testimony, as of status, qualifications, privileges, or the truth of something.

gift certificate (gift ser-tif-i-kit): noun

A certificate entitling the bearer to select merchandise of a specified cash value from a store, usually presented as a gift.