rot, decay, sour
腐 centers on organic breakdown: rotting, decaying, or turning sour. The idea is that something once fresh spoils over time.
腐 combines 府 (which likely contributes the sound) with 肉 (flesh), suggesting flesh that has gone bad. The modern form keeps this phono-semantic structure.
Inside a government office (府) there is meat (肉) that has been left out too long and is now rotting and sour.
For フ, imagine the foul smell of rotting meat: foul -> フ, and the stench fills the government office.
to rot; to go bad; to decay; to spoil; to fester; to decompose; to turn sour (e.g. milk)
tofu; bean curd; beancurd
decomposition; putrefaction; putrescence; spoilage
rot; decay; erosion
rottenness; decay; corruption
stale; hackneyed; clichéd
rotting; spoiling; decaying; corroding
preservation from decay; prevention of putrefaction; embalmment; antisepsis
to speak ill of
boiled tofu
(undesirable but) inseparable relationship
unused possession
taking great pains (to do); making every effort; having a lot of trouble (doing); racking one's brains
sulkiness
future trouble
decomposition; ulceration
smell of something rotten; rotten smell
humus; leaf mold; leaf mould; mulch
carrion; decaying flesh; tainted meat
decay; deterioration; rot