Meaning of proof-of-purchase

proof-of-pur•chase

Pronunciation: (prf'uv-pûr'chus), [key]
— pl. proofs-of-pur•chase.
  1. a sales slip, label, box top, or other item associated with a product that is presentable as evidence of actual purchase, as for claiming a refund or rebate.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.