noun
Chinese yam (Dioscorea opposita variety)
Refers specifically to a variety of Chinese yam, often used in Japanese cuisine for its sticky texture.
大和芋はとろろご飯に使われることが多い。
Chinese yam is often used in tororo gohan (grated yam over rice).
noun
Japanese yam (Dioscorea japonica variety)
Refers to a variety of Japanese yam, similar to the Chinese yam but botanically distinct. In everyday usage, the distinction is often blurred.
この大和芋は粘りが強くて美味しい。
This Japanese yam is very sticky and delicious.
大和 (Yamato, old name for Japan) + 芋 (imo, yam/potato). The name suggests a traditional Japanese variety, though the term now covers both Chinese and Japanese yam varieties.