decay

UK/dɪˈkeɪ/US/diˈkeɪ/

verbB2Common in everyday speech and writing · #5,868 of 15,258leans written

Other forms: decaying, decayed, decays

To decay is to rot slowly, or to fall into a worse state. Tooth decay, the building decayed, decay into fragments.

It covers rot in living matter, decline in institutions and the physics of a radioactive atom breaking down, and in each the word means going to pieces over time without anybody doing anything. Tooth decay is caused by acid from bacteria, not by sugar directly.

Definitions of decay

1verbdecayTo rot slowly, or to fall into a worse state.B2
“Fallen leaves slowly decay on the forest floor and feed the soil.”

decay is a rotting.

Where it comes from

Anglo-Norman decheoir comes from Latin decadere, to fall down — de, down, plus cadere, to fall.

Proto-Indo-European
*ḱh₂d-
Latin
dēcidō — to fall down, to fail, sink or perish
Vulgar Latin
*dēcadere
Anglo-Norman
decheoir — to fall away, decay, decline
Middle English
decaien — to decrease, diminish
English, today
decay

Built from

decai · Middle English — deterioration, decline in value
de- · Latin — of, from, away, down
cadō · Latin — to fall

From Middle English decaien (“to decrease, diminish”) and decai (“deterioration, decline in value”), from Anglo-Norman decheoir (“to fall away, decay, decline”), from Vulgar Latin dēcadere, etymologically restored form of Latin dēcidō (“to fall down, to fail, sink or perish”), from de- (“of, from, away, down”) + cadō (“to fall”). Compare decadent and decadence.

Etymology from Wiktionary, CC BY-SA

Practise this word

decay in the wild

The parent nucleus transforms or "decays" into a daughter product, with a mass number that is reduced by four and an atomic number that is reduced by two.
Alpha decay
For example, uranium-238 undergoes alpha decay to form thorium-234.
Alpha decay
The probability of a nuclide decaying due to beta and other forms of decay is determined by its nuclear binding energy.
Beta decay
The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable atoms survive.
Half-life
The nucleus may remain in an excited state following this decay, from which it rapidly relaxes by emitting gamma rays.
Proton decay

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From Wikipedia, CC BY-SA 4.0. These sentences were written by other people about their own subjects; they are here to show the word at work, not as anybody’s opinion.

Related words

the cadō family

case

decay — used about once every 1,633 pages · #5,868 · point at the bar for the others

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