Decay

To pass gradually from a sound, prosperous, or perfect state, to one of imperfection, adversity, or dissolution; to waste away; to decline; to fail; to become weak, corrupt, or disintegrated; to rot; to perish; as, a tree decays; fortunes decay; hopes decay.

To cause to decay; to impair.

To destroy.

Gradual failure of health, strength, soundness, prosperity, or of any species of excellence or perfection; tendency toward dissolution or extinction; corruption; rottenness; decline; deterioration; as, the decay of the body; the decay of virtue; the decay of the Roman empire; a castle in decay.

Destruction; death.

Cause of decay.

the spontaneous disintegration of a radioactive substance along with the emission of ionizing radiation

the organic phenomenon of rotting

an inferior state resulting from the process of decaying; "the corpse was in an advanced state of decay"; "the house had fallen into a serious state of decay and disrepair"