Definition of flagons:
(n) :
A large vessel resembling a jug, usually with a handle, lid, and spout, for serving drinks such as cider or wine at a table; specifically (Christianity), such a vessel used to hold the wine for the ritual of Holy Communion.
(n) :
A flagon and its contents; as much as fills such a vessel.
(n) :
The amount that such a bottle holds, about 2 pints or 1 litre.
(n) :
(archaic) A large bottle for drinks such as beer, cider, or wine; also, a bottle with a cap used by travellers.