water yam; winged yam; purple yam
Refers to the plant Dioscorea alata, a type of yam. Often used in cooking; purple varieties are known as ube in Filipino cuisine.
Water yam is often used in Okinawan cuisine.
Purple yam is often used in sweets.
The Japanese name ダイジョ is likely derived from the Chinese name 大薯 (dàshǔ), literally 'big yam'.