Water chestnut is a fruit or vegetable?

The water chestnut is actually neither a nut nor a chestnut, but a vegetable. It is an aquatic plant that grows in marshes, swamps, and other wet areas. The edible part of the water chestnut is the corm, which is the swollen underground stem of the plant. Water chestnuts are crunchy and have a slightly sweet flavor. They are often used in Asian cooking, and can be eaten raw or cooked.