E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
That part of the helmet which lifted up to enable the wearer to drink. Similarly bever, the afternoon draught in the harvest-field, called fourss. (Italian, bevere, to drink; Spanish, beber; Latin, bibo; French, buveur, a drinker; Armoric, beuvrauh, beverage, etc.)