water chestnut

American  

noun

1. any aquatic plant of the genus Trapa, bearing an edible, nutlike fruit, especially T. natans, of the Old World.

2. the fruit itself.

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water chestnut British  

noun

1. Also called: water caltrop.  a floating aquatic onagraceous plant, Trapa natans, of Asia, having four-pronged edible nutlike fruits

2. a Chinese cyperaceous plant, Eleocharis tuberosa, with an edible succulent corm

3. the corm of the Chinese water chestnut, used in Oriental cookery

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Etymology

Origin of water chestnut

First recorded in 1850–55