Nathan Bailey's An Universal Etymological English Dictionary gives "CELLARIST – one who keeps a Cella, or Buttery; the Butler in a religious House or Monastery."
After the dissolution of the monasteries, the buttery in large houses and colleges became a place for barrels, bottles, or butts of alcoholic drink, and from which they were brought up and served into the Great Hall.
The screens passage generally had two or three doors on the side opposite its entrances into the Great Hall, which led, respectively, to the buttery, kitchen, and pantry, each of which formed separate household departments.
[4] Later the monk butterer became the smartly suited "butler" that we know today [citation needed], the household officer in charge of the buttery, and possibly also its provisioner (i.e., the sourcing and purchasing of wine).
[citation needed] Later, as household staff in the great houses became reduced, the butler also became required to personally serve wine to his lord and guests at banquets.
From the mid-17th century, as it became the custom for servants and their offices to be less conspicuous and sited far from the principal reception rooms, the Great Hall and its neighbouring buttery and pantry lost their original uses.