Stopper (plug) - Definition and Overview

A stopper is a truncated conical piece of rubber or cork used to close off a glass tube, piece of laboratory glassware, a wine bottle or barrel and other containers with orifices. A rubber stopper is sometimes called a rubber bung, and a cork stopper is called cork.

Before cork came into common use, wine bottles were sealed with custom ground glass stoppers, but these were not very airtight and had the unfortunate tendency to shatter. However, ground glass stoppers are still commonly used with laboratory glassware, mainly because of their nonreactivity.

Nowdays, because of the increasingly limited availabilty of cork, some wineries have switched to synthetic cork instead of natural, this has the advantage that the synthetic corks do not dry out and thus the wine bottles do not have to be shipped laying on their sides. It also eliminates cork taint.