Definitions

1. noun

A device, typically a metal or plastic plug, used to seal a hole in a cylinder, particularly in a rifle or shotgun, to improve its accuracy and prevent damage.

“The gunsmith installed a tompion to prevent damage to the rifle’s barrel during storage.”

2. verb

To seal a hole or opening in a cylinder, typically with a tompion.

“The hunter tompioned the shotgun to prevent debris from entering the barrel.”