Where does “尻尾” come from?

尻尾 (Japanese) comes from Japanese 尾, from Old Japanese 尾.

尻尾 (Japanese): tail

Definitions

Step	Language	Word	Meaning
1	Japanese	尾	a tail; the foot of a mountain; the end of...
2	Old Japanese	尾	—

尻尾 — Etymology, Origin & Word History | Etymology Explorer