Bung

A bung is a stopper used to seal the opening of a container such as a bottle, barrel, drum, or pipe. Bungs are typically cylindrical and made from cork, rubber, or plastic, and they are designed to be pressed or driven into a hole to prevent leakage while remaining removable for access.

In brewing and winemaking, bungs seal fermentation vessels and barrels. A traditional wooden barrel has a bunghole that is plugged with a bung; many bungs include an air vent or airlock feature to allow gases to escape during fermentation while limiting oxygen entry. In bottles and jars, bungs may be solid stoppers or corks.

In carpentry and furniture making, a wooden bung is a short cylindrical plug used to fill the end of a drilled hole or to conceal a mortise or dowel joint. Such plugs are usually cut from the same wood as the surrounding stock and are finished flush with the surface.

The origin of the term bung is uncertain, but the word has been used in English for centuries to describe a removable plug or stopper.