A “drink” between meals. (Italian, bevere, to drink- our beverage; Latin, bibere—our im-bibe). At Eton they used to have “Bever days,” when extra beer and bread were served during the afternoon in the College Hall to scholars, and any friends whom they might bring in.
“He . . . will devour three breakfasts . . . without prejudice to his bevers.” —Beaumont and Fletcher: Woman Hater, i. 3.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894