Stopper (plug)
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.
