flowing water does not rot; used as a metaphor to mean that constant activity or practice prevents stagnation and keeps one healthy or sharp

lit. a door hinge never becomes worm-eaten; used to describe how regular activity or exercise prevents things from rotting or losing their function, often used in the phrase 流水不腐 liú​shuǐ​bù​fǔ

flowing or running water

Negative adverb used before verbs, adjectives, and other adverbs to indicate negation; also used as a bound-form prefix to form terms with opposite meanings

(bound form) rotten; putrid; decayed; corroded

(bound form) a single-leaf door; an entrance or opening to a house

(bound form) the hinge or axis of a door; a mechanical pivot

Negative adverb used before verbs, adjectives, and other adverbs to indicate negation; also used as a bound-form prefix to form terms with opposite meanings

(bound form) to eat into; to corrode; to be moth-eaten or worm-eaten