- a Chinese sedge (Eleocharis dulcis) with erect, cylindrical leaves, growing in dense clumps in water
- the large, button-shaped, submerged tubers of this plant, used in Chinese cooking
- a floating aquatic weed (Trapa natans) of the water-chestnut family, with black, hard, horned fruit, the seed of which is sometimes eaten
- a. A tropical Asian aquatic sedge (Eleocharis dulcis) having cylindrical stems and widely cultivated for its edible corm.b. The crisp nutty corm of this plant, used in Asian cooking.
- A floating aquatic plant (Trapa natans) native to Eurasia and Africa, cultivated as an ornamental and for its edible four-pronged nutlike fruit, and occurring widely as an aquatic weed. Also called caltrop, water caltrop.
(countable and uncountable, plural water chestnuts)
- (uncountable) Eleocharis dulcis, grown for its edible corm, used in Asian cooking.
- (countable) A corm of a plant of this species.
- water caltrop.
- The usage of water chestnut for the water caltrop is best avoided, so as to prevent confusion