Refers specifically to the plant Eleocharis dulcis var. tuberosa, known for its edible corms. In Japanese, it is a botanical term, not an everyday food word.
Chinese water chestnuts are cultivated in wetlands.
Katakana spelling is standard for this plant name; usually written in kana.
Kanji spelling is rare and mainly found in older or specialized botanical texts.
The Japanese name オオクログワイ literally means 'large black arrowhead', likely referring to the plant's appearance. The exact derivation is uncertain.