偃
エン, ふ.せる

dam, weir

JLPT0 G13 S0 F5000

As per 匽# (set in place) + 人 person → *lay (the body) down/low*; *lay (a weapon/tool) down* and take a rest. *Weir* is a borrowed meaning, via 堰.

[Full Kanji Etymology List]