コウ, ゴ, お.りる, お.ろす, ふ.る, ふ.り, くだ.る, くだ.す, ふり, ふる
descend, precipitate, fall, surrender
JLPT3 G6 S10 F596
The relevant oracle bone form of 夅 is a depiction of legs bending as they descend a hill. 降 is 夅# + 阜 piled earth (for emphasis/clarification) → *descend* a high hill → *fall*; *get off/out*; *lower*; *unload*; *transfer*. Other extended meanings from "fall" include *defeat*; *retire*; *give up*; *to rain*; *to snow*; and *abort* (a fetus).
[Full Kanji Etymology List]