capper

[ kap-er ]
/ ˈkæp ər /

noun

a person or thing that caps.
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.
Slang. an informer, especially for gamblers.
Slang. a by-bidder at an auction.

Origin of capper

1350–1400 (for sense “cap maker”); 1580–90 (for def 1); Middle English; see cap1, -er1
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

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