Bungeye

Part of speech: noun

Definitions

1. The opening in the side of a barrel or cask through which it is filled and emptied, sealed with a stopper
2. The hole in a wooden cask into which a bung is fitted to close it after filling
3. A cask's filling aperture, the opening that a plug or stopper is driven into to seal the contents

Etymology: The "eye" in "bungeye" is the same word as the organ of sight, but in older English it also meant any small opening, as in the eye of a needle. A bungeye is the hole in a cask's side through which it is filled and emptied, and the stopper that closes it is the bung. Coopers and brewers used the term for centuries, long before it appeared in general dictionaries. "Bung" is probably borrowed from Middle Dutch or Middle Low German, where a similar word named a stopper. English speakers then combined it with "eye" to name the specific opening the stopper fits into. The compound is therefore a description of function: a stopper's opening, named for the eye-like hole it leaves in the barrel.