DEMIJOHN Meaning of DEMIJOHN in English ■ noun a bulbous narrow-necked bottle holding from 3 to 10 gallons of liquid.OriginC18: prob. an alt. of Fr. dame-jeanne 'Lady Jane', assoc. with demi- and the given name John . Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004