Demijohn originally referred to any glass vessel with a large body and small neck. The word presumably comes from the French dame-jeanne, literally "Lady Jane", as a popular appellation; this word is first attested in France in the 17th century.
Green glass hue
Large: 19.5'' L x 16'' W x 25'' H
Medium: 12'' x L 10'' W x 17'' H
Small: 7'' L x 7'' W x 12.5'' H