decay

verb
de·​cay | \ di-ˈkā How to pronounce decay (audio) \
decayed; decaying; decays

Definition of decay

 (Entry 1 of 2)

intransitive verb

1 : to decline from a sound or prosperous condition a decaying empire
2 : to decrease usually gradually in size, quantity, activity, or force The three voices … decayed and died out upon her ear.— Thomas Hardy
3 : to fall into ruin the city's decaying neighborhoods
4 : to decline in health, strength, or vigor Her mind is beginning to decay with age. believes that the moral fiber of our society is decaying
5 : to undergo decomposition decaying fruit Her teeth were decaying. … most isotopes of copper decay quickly, but two are stable: Cu-63 and Cu-65.— David E. Thomas

transitive verb

1 obsolete : to cause to decay : impair infirmity that decays the wise— William Shakespeare
2 : to destroy by decomposition wood decayed by bacteria

decay

noun

Definition of decay (Entry 2 of 2)

1 : gradual decline in strength, soundness, or prosperity or in degree of excellence or perfection the decay of the public school system
2 : a wasting or wearing away : ruin a neighborhood that had fallen into decay
3 obsolete : destruction, death … sullen presage of your own decay.— Shakespeare
4a : rot The material is … resistant to fire, decay and termites …— Jack McClintock specifically : aerobic decomposition of proteins chiefly by bacteria
b : the product of decay tooth decay
5 : a decline in health or vigor mental decay
6 : decrease in quantity, activity, or force: such as
a chemistry : spontaneous decrease in the number of radioactive atoms in radioactive material
b physics : spontaneous disintegration (as of an atom or a particle)

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Other Words from decay

Verb

decayer noun

Choose the Right Synonym for decay

Verb

decay, decompose, rot, putrefy, spoil mean to undergo destructive dissolution. decay implies a slow change from a state of soundness or perfection. a decaying mansion decompose stresses a breaking down by chemical change and when applied to organic matter a corruption. the strong odor of decomposing vegetation rot is a close synonym of decompose and often connotes foulness. fruit was left to rot in warehouses putrefy implies the rotting of animal matter and offensiveness to sight and smell. corpses putrefying on the battlefield spoil applies chiefly to the decomposition of foods. keep the ham from spoiling

Examples of decay in a Sentence

Verb

the smell of decaying rubbish dead plants and leaves decayed by bacteria She believes that the moral fiber of our society is decaying. our decaying public school system The city's neighborhoods are decaying.

Noun

the decay of dead plants and leaves She writes about the moral decay of our society. the patient's physical and mental decay The city's neighborhoods are in slow decay.
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Recent Examples on the Web: Verb

Females lay their eggs on the surface or inside fruit that's overripe, rotting, or decaying. Natalie Schumann, Country Living, "How to Get Rid of Fruit Flies for Good," 9 May 2019 By measuring how many of these elements have already decayed, the scientists can calculate when the neutron star collision happened. Avery Thompson, Popular Mechanics, "Two Neutron Stars Exploded in Our Cosmic Backyard Billions of Years Ago," 3 May 2019 Videotape is decaying at a much more frightening pace because it wasn’t made to last. Nina Metz, chicagotribune.com, "Screen old home videocassettes and re-live the '80s," 2 Apr. 2018 One possibility is that sometimes neutrons decay into a baryonic dark matter particle. Chris Lee, Ars Technica, "Dark matter not at the core of neutron stars," 9 Aug. 2018 Only one of the two types of neutron decay experiments would be sensitive to neutrons decaying into dark matter. Clara Moskowitz, Scientific American, "Missing Neutrons May Lead a Secret Life as Dark Matter," 29 Jan. 2018 Moments like this, which touch on the way that Castle Rock is decaying as an isolated relic of American history, are more unsettling than those that suggest that a supernatural curse is what’s really affecting the people who live there. Karen Han, Vox, "Hulu’s Castle Rock gets what makes Stephen King so scary," 20 July 2018 The strong magnetic field allows the axion to decay into a photon. Chris Lee, Ars Technica, "Pulsars could convert dark matter into something we could see," 20 Dec. 2018 And employment growth doesn’t necessarily vary among firms based on how many workers are in unions, so there’s no reason for union membership to decay as firms with more union members do worse. Dylan Matthews, Vox, "The emerging plan to save the American labor movement," 9 Apr. 2018

Recent Examples on the Web: Noun

Xenon-124 is a radioactive isotope that takes about 1.8 sextillion years to decay, on average. Avery Thompson, Popular Mechanics, "Dark Matter Scientists Observe the Rarest Event in History," 27 Apr. 2019 Entrepreneurs resist urban decay by opening new stores, restaurants and other establishments. Stephen Miller, WSJ, "‘The Ravages of Capitalism’," 21 Jan. 2019 Newark, the largest city in New Jersey and long a symbol of urban decay, has had a rush of development downtown that has encouraged new businesses to open. New York Times, "A City Founded by Alexander Hamilton Sets the Stage for Its Next Act," 5 July 2018 Empty and dark, the old Colonial Revival structure was seen as an emblem of urban decay. Inga Saffron, Philly.com, "One building's journey from a place of incarceration, to a venue of liberation," 12 Apr. 2018 Absent an economic revival, the EU will continue to decay and could dissolve. WSJ, "The Lesson From Europe Is In What Policies to Avoid," 4 Mar. 2019 In the case of radioactive material, how long the substance is dangerous depends on how quickly its atoms lose energy, a process known as radioactive decay and measured by what’s called a half-life. Vera Thoss, Washington Post, "How the nerve agent in the spy attack and other toxins cause widespread contamination," 24 Mar. 2018 The rest of the core materials may experience radioactive decay and tidal forces to stay hot, which also heats up the water into super-hot jets moving toward the north and south pole. John Wenz, Popular Mechanics, "Enceladus Has a Porous Core That Keeps Its Ocean Hot," 6 Nov. 2017 There is no known cure for the disease, which causes the leaves on the tree to turn yellow, the roots to decay and bitter fruits to fall off the dying branches prematurely. Sena Christian, Newsweek, "Breakfast in Post-Apocalypse America: Inside Colorado's Fort Knox of Food," 19 Nov. 2015

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'decay.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of decay

Verb

15th century, in the meaning defined at intransitive sense 1

Noun

15th century, in the meaning defined at sense 1

History and Etymology for decay

Verb and Noun

Middle English, from Anglo-French decaïr, from Late Latin decadere to fall, sink, from Latin de- + cadere to fall — more at chance

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Statistics for decay

Last Updated

11 Jun 2019

Look-up Popularity

Time Traveler for decay

The first known use of decay was in the 15th century

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More Definitions for decay

decay

verb

English Language Learners Definition of decay

 (Entry 1 of 2)

: to be slowly destroyed by natural processes : to be slowly broken down by the natural processes that destroy a dead plant or body
: to slowly lose strength, health, etc.
of a building, area, etc. : to go slowly from a bad condition to a worse condition : to slowly enter a state of ruin

decay

noun

English Language Learners Definition of decay (Entry 2 of 2)

: the process or result of being slowly destroyed by natural processes
: the slow loss of strength, health, etc.
of a building, area, etc. : the process or result of going slowly from a bad condition to a worse condition

decay

verb
de·​cay | \ di-ˈkā How to pronounce decay (audio) \
decayed; decaying

Kids Definition of decay

 (Entry 1 of 2)

1 : to break down or cause to break down slowly by natural processes Fruit decayed on the ground. Sugar decays teeth.
2 : to slowly worsen in condition The old theater decayed.

decay

noun

Kids Definition of decay (Entry 2 of 2)

1 : the process or result of slowly breaking down by natural processes The schoolhouse being deserted soon fell to decay— Washington Irving, “Sleepy Hollow”
2 : a gradual worsening in condition a decay in manners
3 : a natural change of a radioactive element into another form of the same element or into a different element
de·​cay | \ di-ˈkā How to pronounce decay (audio) \

Medical Definition of decay

 (Entry 1 of 2)

: to undergo decomposition

transitive verb

: to destroy by decomposition

decay

noun

Medical Definition of decay (Entry 2 of 2)

1a : rot sense 1 specifically : aerobic decomposition of proteins chiefly by bacteria
b : the product of decay
2a : spontaneous decrease in the number of radioactive atoms in radioactive material
b : spontaneous disintegration (as of an atom or a nuclear particle)

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More from Merriam-Webster on decay

Rhyming Dictionary: Words that rhyme with decay

Thesaurus: All synonyms and antonyms for decay

Spanish Central: Translation of decay

Nglish: Translation of decay for Spanish Speakers

Britannica English: Translation of decay for Arabic Speakers

Britannica.com: Encyclopedia article about decay

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