From Longman Dictionary of Contemporary Englishdecayde‧cay1 /dɪˈkeɪ/ ●●○ verb 1 [intransitive, transitive]DECAY to be slowly destroyed by a natural chemical process, or to make something do this Her body was already starting to decay. Most archaeological finds are broken, damaged, or decayed. decaying organic matterRegisterIn everyday English, people usually say rot rather than decay when talking about food:There was a smell of rotting vegetables.2 [intransitive]DECAY if buildings, structures, or areas decay, their condition gradually becomes worse Hundreds of historic buildings are being allowed to decay. Britain’s decaying inner cities3 [intransitive]LESS if traditional beliefs, standards etc decay, people do not believe in them or support them anymore SYN decline In Orthodox Europe, mass religion seems to have decayed less.THESAURUSdecay to be slowly destroyed by a natural chemical process – use this especially about natural things such as wood or plants, or about teethThe leaves decay and enrich the soil.He had bad breath and decaying teeth.The fabric slowly began to decay. rot to decay. Rot is less formal than decay and is more common in everyday EnglishThe fruit was left to rot on the ground.rotting teethMost of the wood under the paint had rotted.the smell of rotting vegetation (=decaying leaves and plants)go off British English if food goes off, it starts to smell bad and is no longer be safe to eatI think the milk’s gone off.The meat smells as if it's gone off.spoil if food spoils, it starts to decay, so that it is no longer safe to eat. Spoil is more formal and is less common in everyday British English than go offFood left in the sun will quickly start to spoil.go mouldy British English, moldy American English to begin to have a soft green or black substance growing on the surface of the food, so that it is not good to eat anymoreUgh, the cheese has gone mouldy!decompose formal to decay – use this especially about dead plants or fleshleaves decomposing on the forest floorputrefy formal to decay and have a very bad smell – use this especially about flesh or plantsAfter two days, the body was already beginning to putrefy.putrefying meatbiodegrade to decay naturally into substances that do not harm the environment – use this especially about man-made materials and chemicalsUnlike many other materials, plastic does not biodegrade. → See Verb table
Examples from the Corpus
decay• Freezing conditions will stop most things from decaying.• Now even elections seem to be decaying.• If you eat too many sweets, it'll make your teeth decay.• Some of the apples lying on the ground had already begun to decay.• A few species laid eggs beneath mounds of rotten vegetation that warmed as it decayed.• Bones signify the eternal being which does not decay.• There was now not the slightest doubt that Hsu was decaying and losing her structural integrity.• The decaying body of a man was found in a vacant warehouse.• It decays by a scheme that has two paths.• This decaying city was once the busiest port in the world.• However, objects decay despite our best efforts to conserve them.• the decaying moral values of American society• In a warm climate where flesh decays rapidly, there is more risk of infection from dead animals.• In one path, the 40K decays to a calcium isotope, 40Ca.• The buildings still stand, slowly decaying, without past or future, or any links with the surrounding land.decaydecay2 ●●○ noun [uncountable] 1 DECAYthe natural chemical change that causes the slow destruction of something old cars in various stages of decay tooth decay2 DESTROYthe gradual destruction of buildings, structures etc because they have not been cared for poverty and urban decayfall into (a state of) decay During the war, the area fell into decay.3 LESSthe gradual destruction of ideas, beliefs, social or political systems etc moral decayCOLLOCATIONSverbscause decayBacteria stick to food and cause decay.prevent decayYou can use a preservative on the wood to prevent further decay.ADJECTIVES/NOUN + decay tooth/dental decayEating too much sugar causes tooth decay.natural decayEverything in our environment is subject to natural decay.phrasesthe process of decayThe natural processes of decay gradually destroys archaeological sites.a sign of decayI couldn't see any signs of decay on the fruit. Examples from the Corpus
decay• And it's the bodily imperfections and decay which lead us to desire a permanence of the human essence.• I have noticed decay in some of the floorboards.• Tiny organisms that live in the soil assist the process of decay.• Now, however, the great Latin cities fell prey to widespread depopulation, economic decline, and physical decay.• Without renewal, decay becomes irredeemable.• But nomatterwhat cosmetics we use, what exercises we do, the decay of our bodies moves inexorably forward.• The decay constant F includes any process that destroys c1, c2 or their correlation.• the decay of the central government in Russia• Brushing your teeth regularly helps to fight against tooth decay.• Its rough surface traps the microflora responsible for halitosis and tooth decay.• An optimistic theory of evolutionary progress was surreptitiously beginning to replace the pessimistic doctrine of universal decay.stages of decay• The place was littered with barbed wire and rotting lumber and a dozen old boats in various stages of decay.• The organic matter in soil consists of plant and animal debris or waste in varying stages of decay.fall into (a state of) decay• From the time of Laurence little work was carried out on the Palace and it was again allowed to fall into decay.Origin decay1 (1400-1500) Old North French decaïr, from Late Latin decadere “to fall, sink” 