capper

Short definition from Wiktionary

Noun

1. 1
   A device or person that applies caps, as to bullets or bottles.
2. 2
   A person that makes or sells caps.
3. 3
   A finale; something that is conclusively better, or "caps it all off".
4. 4
   A by-bidder; a decoy for gamblers.
5. 5
   A person who records a television broadcast to their computer.
6. 6
   A person who caps i.e. is inclined to untruth, a fibber.

Proper noun

1. 1
   A surname.