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 Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for capper

Contemporary Examples of capper

Historical Examples of capper

  • As a capper he digs up that envelop, to show her there needn't be any hitch in the program.

    Shorty McCabe

    Sewell Ford

  • It is amazing the many who were willing to play the part of capper in this game.

  • Rawlinson reported that Capper with two brigades was still in Ghent.


    John French, Viscount of Ypres

  • He is a sort of bouncer, or capper for that gambling joint run by Plimsoll.

    Rimrock Trail

    J. Allan Dunn

  • Capper (appearing quietly from room L., and locking the door behind him).