痩
ソウ, チュウ, シュウ, シュ, や.せる
get thin
JLPT0 G7 S12 F5000
The variant form
瘦
is as per
叟
# (narrow/thin) +
疒
illness → illness that causes one to *grow thin* → (land that becomes) *sterile/barren*.
[Full Kanji Etymology List]