decay

1 of 2

verb

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

intransitive verb

1
: 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
2
: 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
3
: to fall into ruin
the city's decaying neighborhoods
4
: to decline from a sound or prosperous condition
a decaying empire
5
: to decrease usually gradually in size, quantity, activity, or force
The three voices … decayed and died out upon her ear.Thomas Hardy

transitive verb

1
: to destroy by decomposition
wood decayed by bacteria
2
obsolete : to cause to decay : impair
Infirmity, that decays the wise …William Shakespeare
decayer noun

decay

2 of 2

noun

1
a
: 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
2
: gradual decline in strength, soundness, or prosperity or in degree of excellence or perfection
the decay of the public school system
3
: a decline in health or vigor
mental decay
4
: a wasting or wearing away : ruin
a neighborhood that had fallen into decay
5
: 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)
6
obsolete : destruction, death
… sullen presage of your own decay.Shakespeare
Choose the Right Synonym for decay

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.
Recent Examples on the Web
Verb
What doesn’t decay this winter can be mulched up next spring. Jeff Lowenfels, Anchorage Daily News, 22 Sep. 2022 In particular, many theorists have wondered how the great complexity of life can be reconciled with the laws of thermodynamics that suggest that all systems must inevitably decay to a state of greatest disorder. The Physics Arxiv Blog, Discover Magazine, 29 Apr. 2022 See all Example Sentences for decay 

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'decay.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

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

First Known Use

Verb

15th century, in the meaning defined at intransitive sense 4

Noun

15th century, in the meaning defined at sense 2

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

Dictionary Entries Near decay

Cite this Entry

“Decay.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/decay. Accessed 28 May. 2024.

Kids Definition

decay

1 of 2 verb
de·​cay di-ˈkā How to pronounce decay (audio)
1
: to lose soundness, health, strength, or vigor
2
: to go through or cause to go through decomposition
a radioactive element decays
apples that decayed in storage

decay

2 of 2 noun
1
: gradual loss of strength, soundness, health, or vigor
2
3
: a natural decrease in the number of radioactive atoms in radioactive material

Medical Definition

decay

1 of 2 intransitive verb
de·​cay di-ˈkā How to pronounce decay (audio)
: to undergo decomposition

transitive verb

: to destroy by decomposition

decay

2 of 2 noun
1
a
: rot sense 1
specifically : aerobic decomposition of proteins chiefly by bacteria
b
: the product of decay
2
a
: 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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