Origin of demijohnFrench dame-jeanne, demijohn, literally , Dame Jeanne: probably origin, originally a fanciful name for the bottle
A large, narrow-necked glass or earthenware bottle, usually encased in wickerwork.
Origin of demijohnProbably alteration of French dame-Jeanne dame lady ; see dame . Jeanne personal name
From French dame-jeanne, of uncertain origin.