Chestnut relates either to the sweet chestnut or water chestnut.
The sweet chestnut has been grown for many centuries and used in soups, stews and stuffings. Chestnut is the only nut that is treated as a vegetable, because it contains more starch and less oil than other nuts it can be cooked differently. Sweet chestnuts can be eaten whole, either roasted, boiled or steamed. Once shelled, they are preserved whole in sugar or syrup as marrons glacés. Chestnuts can also be chopped and used in stuffings or with vegetables such as red cabbage, or ground into flour.
Water chestnuts come in two varieties: Trapa natans has an edible seed and a floury texture and is eaten raw, roasted and boiled in central Europe and Asia. Trapa bicornis, ling, is grown in China, Korea and Japan and its seeds are eaten boiled, or preserved in honey and sugar or used to make flour.
The Chinese water chestnut, pi tsi, is a tuber that is grown in China and Japan. The Chinese water chestnut is used sliced as a vegetable and is usually bought canned in Asia.
Dowell, P., Bailey, A. (1980) The Book of Ingredients, Dorling Kindersley. ISBN 0718119150.