drooping tail
Refers to a tail that hangs down, often used in descriptions of animals or mythical creatures. Can also appear in compound terms like 垂り尾形 (a type of sword blade shape).
The dog approached, wagging its drooping tail.
In the old picture scroll, a dragon with a drooping tail is depicted.
Compound of 垂り (shidari, 'drooping') + 尾 (o, 'tail'). The exact historical derivation is uncertain, but the spelling is conventionally associated with the meaning.