decay
Americanverb (used without object)
-
decays,
present (3rd person singular)
-
decayed,
past participle, past
-
decaying
present participle
-
to become decomposed; rot.
vegetation that was decaying.
- Synonyms:
- putrefy, wither, degenerate
-
to decline in excellence, prosperity, health, etc.; deteriorate.
-
Physics. (of a radioactive nucleus) to change spontaneously into one or more different nuclei in a process in which atomic particles, as alpha particles, are emitted from the nucleus, electrons are captured or lost, or fission takes place.
verb (used with object)
-
decays,
present (3rd person singular)
-
decayed,
past participle, past
-
decaying
present participle
noun
-
Decay made the wood unsuitable for use.
- Synonyms:
- putrefaction
-
a gradual falling into an inferior condition; progressive decline.
the decay of international relations; the decay of the Aztec civilizations.
-
decline in or loss of strength, health, intellect, etc..
His mental decay is distressing.
- Synonyms:
- degeneration, dilapidation, impairment, decadence, deterioration
-
Physics. radioactive decay.
-
Aerospace. the progressive, accelerating reduction in orbital parameters, particularly apogee and perigee, of a spacecraft due to atmospheric drag.
verb
-
to decline or cause to decline gradually in health, prosperity, excellence, etc; deteriorate; waste away
-
to rot or cause to rot as a result of bacterial, fungal, or chemical action; decompose
-
Also: disintegrate. (intr) physics
-
(of an atomic nucleus) to undergo radioactive disintegration
-
(of an elementary particle) to transform into two or more different elementary particles
-
-
(intr) physics (of a stored charge, magnetic flux, etc) to decrease gradually when the source of energy has been removed
noun
-
the process of decline, as in health, mentality, beauty, etc
-
the state brought about by this process
-
decomposition, as of vegetable matter
-
rotten or decayed matter
the dentist drilled out the decay
-
physics
-
a spontaneous transformation of an elementary particle into two or more different particles
-
of an excited atom or molecule, losing energy by the spontaneous emission of photons
-
physics a gradual decrease of a stored charge, magnetic flux, current, etc, when the source of energy has been removed See also time constant
-
music the fading away of a note
-
The breaking down or rotting of organic matter through the action of bacteria, fungi, or other organisms; decomposition.
-
The spontaneous transformation of a relatively unstable particle into a set of new particles. For example, a pion decays spontaneously into a muon and an antineutrino. The decay of heavy or unstable atomic nuclei (such as uranium or carbon-10) into more stable nuclei and emitted particles is called radioactive decay. The study of particle decay is fundamental to subatomic physics.
-
See more at fundamental force radioactive decay
Synonym Usage
Decay, decompose, disintegrate, rot imply a deterioration or falling away from a sound condition. Decay implies either entire or partial deterioration by progressive natural changes: Teeth decay. Decompose suggests the reducing of a substance to its component elements: Moisture makes some chemical compounds decompose. Disintegrate emphasizes the breaking up, going to pieces, or wearing away of anything, so that its original wholeness is impaired: Rocks disintegrate. Rot is a stronger word than decay and is especially applied to decaying vegetable matter, which may or may not emit offensive odors: Potatoes rot.
Other Word Forms
Derived Forms
-
semidecaynoun
-
redecayverb
-
decayableadjective
-
decayednessadjective
-
decaylessadjective
-
nondecayedadjective
-
nondecayingadjective
-
semidecayedadjective
-
undecayableadjective
-
undecayedadjective
-
undecayingadjective
Inflected Forms
Participles
Conjugated Forms
Present
-
decaysimple
-
decayssimple
-
have decayedperfect
-
has decayedperfect
-
am decayingprogressive
-
are decayingprogressive
-
is decayingprogressive
-
have been decayingperfect progressive
-
has been decayingperfect progressive
Past
-
decayedsimple
-
had decayedperfect
-
was decayingprogressive
-
were decayingprogressive
-
had been decayingperfect progressive
Future
Etymology
Origin of decay
First recorded in 1425–75; late Middle English verb decayen, decaien, from Old North French decair, equivalent to de- “down” + cair “to fall,” from unattested Vulgar Latin cadēre, for Latin cadere; noun derivative of the verb; see de-.
Explanation
To decay means to rot, decompose, break down. Our bodies—anything organic—will decay after death. Broken sidewalks, potholes, graffiti are all signs of urban decay. Tooth decay is something to avoid. Decay can also mean decline. Anyone, even a great athlete, must exercise regularly to maintain muscle tone—as soon as you stop, the muscles begin to decay. If the strength of the cable signal coming into your house grows weaker over time, you can complain that it has decayed.
Vocabulary lists containing decay
Earth Science - Middle School
Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!
Rocks and Minerals - Introductory
Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!
Earth Science: Natural Resources and the Environment
Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
"It's going to be extremely difficult now. There is this general mood of decay, of a country that's not working properly. A depression."
From BBC ● Oct. 31, 2026
These naturally occurring radioactive forms of elements decay at predictable rates, making them valuable tools for identifying events deep in Earth's environmental history.
From Science Daily ● Oct. 29, 2026
New research suggests that pure, unsweetened cranberry juice can slow the growth of dental plaque and reduce the production of acids that contribute to tooth decay.
From Science Daily ● Oct. 29, 2026
It was a reclamation of beauty standards, in which icons like the Brat singer Teresa Covarrubias adopted the visual markers of shadow and decay, refusing to render themselves more easily readable or palatable.
From Los Angeles Times ● Oct. 28, 2026
The smell was overwhelming, a mixture of sweet perfume and damp decay.
From "City of the Plague God" by Sarwat Chadda
Precise investigations of decays like this are one of the primary goals of the LHCb experiment, and have been since its inception in 1994.
From Science Daily ● May 26, 2026
It contains radium that decays into radon gas, which is radioactive and can cause cancer.
From Barron's ● Oct. 10, 2025
Keeping the truth from someone might not be outright dishonesty, but it’s a rot that decays the same way, just festering at a slower pace.
From Salon ● Apr. 18, 2025
In short, it's a scenario in which the universe continues to both expand and cool - while everything within it dies off, decays, and fades away.
From BBC ● Oct. 31, 2024
As the manure/woodchip mix decays it heats up, warming the barn.
From "The Omnivore's Dilemma" by Michael Pollan
Beneath her boots is peat, built up over thousands of years and consisting of partially decayed plants and organic matter.
From BBC ● Sep. 12, 2026
To investigate the mystery, the researchers measured gamma rays produced as a radioactive copper isotope decayed into zinc.
From Science Daily ● Aug. 21, 2026
Yet, despite this surge of security personnel, basic living conditions have only decayed.
From Slate ● Aug. 11, 2026
“Remote and hybrid work used to be a privilege, but its benefits over in-person work have decayed across the board,” Chris Martin, senior economist at Glassdoor, told MarketWatch.
From MarketWatch ● Jun. 27, 2026
The hobbits crept inside, and sat there upon a floor of old leaves and decayed wood.
From "The Fellowship of the Ring" by J.R.R. Tolkien
A rigorous education in the humanities must fill the student with “wonder, admiration, and, above all, gratitude and humility, without which any attempt to revivify a decaying culture will fail.”
From The Wall Street Journal ● Oct. 30, 2026
True, but the alternative is what we have now: decaying buildings, no reason to maintain them, and a growing stock of potentially affordable empty apartments.
From The Wall Street Journal ● Oct. 19, 2026
Papatsanis used ultrviolet light to illuminate mushrooms known as "beautiful bonnets" growing from a decaying log on the lower slopes of Mount Olympus in Greece.
From BBC ● Oct. 13, 2026
They resumed digging at a sprawling and decaying property, shifting the focus from a battered greenhouse that was the center of attention Tuesday to an area nearer a home.
From Los Angeles Times ● Sep. 30, 2026
When you enter the apartment complex, it feels like entering the courtyard of a dead king and his decaying cement kingdom.
From "Everything Sad Is Untrue" by Daniel Nayeri
Random Word
Spin the wheel and learn a new word!
Get a wordDefinitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
