堕
ダ, お.ちる, くず.す, くず.れる
degenerate, descend to, lapse into
JLPT1 G7 S12 F2087
As per 隋# (collapsing pile of earth) +
土
earth (for emphasis/clarification) → collapsing/falling earth → *fall*; *drop*.
[Full Kanji Etymology List]