Pronunciation: (kap'ur), [key]
1. a person or thing that caps.
2. Also called topper. something that completes or adds to what has preceded it: The capper was that we didn't know each other after all.
3. Slang.an informer, esp. for gamblers.
4. Slang.a by-bidder at an auction.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.