1. (v. i.) 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.

2. (v. t.) To cause to decay; to impair.

3. (v. t.) To destroy.

4. (n.) 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.

5. (n.) Destruction; death.

6. (n.) Cause of decay.

ablate ablation atomization atomize atrophy biodegradability biodegradation break down break up breakup canker caries carrion catalysis catalyst collapse come apart consume contaminate corrode corrosion corrupt corruption crack up crumble crumble into dust crumbling curdle dandruff debilitate decadence decline decompose decomposition decrease defile degenerate degeneration degradability degradation deteriorate deterioration dialysis dilapidate dilapidation diminish disintegrate disintegration disjoin disjunction disorganization disorganize dissociation dissolution dissolve downfall dry rot dwindle ebb enfeeble erode erosion excrement fading failing fall into decay fall to pieces ferment fester filth fission foul matter foulness furfur gangrene go bad go off go to pieces go to pot go to seed hydrolysis hydrolyst incoherence mess mildew mold molder mortification mortify mould moulder muck mucus necrose necrosis obscenity ordure oxidation oxidization perish photolysis pollute pus putrefaction putrefy putresce putrescence putrid matter putridity putridness rancidity rancidness rankle rankness ravages of time resolution rot rottenness rotting ruin rust sap scurf scuz slime slough smut snot sordes sour sphacelate sphacelation sphacelus split splitting spoil spoilage suppurate taint thermolysis tooth decay turn undermine wane waste away wasting weaken weakening wear wear and tear wear away wither work wreck