Definition of “decay” - English Dictionary

“decay” in British English

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decayverb

uk /dɪˈkeɪ/ us /dɪˈkeɪ/

B2 [ I or T ] to become gradually damaged, worse, or less; to cause something to do this:

Sugar makes your teeth decay.
The role of the extended family has been decaying for some time.
Pollution has decayed the surface of the stonework on the front of the cathedral.
the smell of decaying meat

[ I ] specialized physics If a radioactive substance decays, it changes to a different form, producing radiation:

Radioactive uranium decays into stable lead at a known rate.
As the actinium-225 decays, it gives off short-lived, highly energized alpha particles.

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decaynoun [ U ]

uk /dɪˈkeɪ/ us /dɪˈkeɪ/

C2 the process of decaying:

dental/tooth decay
The buildings had started to fall into decay.
This industry has been in decay for some time.

specialized physics the process by which a radioactive substance changes to a different form, producing radiation:

Radon is emitted in the natural decay of radioactive materials in rock and soil.
the decay rate of beryllium-7

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(Definition of “decay” from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)

“decay” in American English

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decaynoun [ U ]

us /dɪˈkeɪ/

damage, or a state that becomes gradually worse:

The dentist says I have a lot of tooth decay.
There’s still too much crime, poverty, and decay in the neighborhood.
Your attitude just contributes to the growing social decay.

decay noun [ U ] (PROCESS)

physics /dɪˈkeɪ/ the process by which a radioactive substance breaks down and sends out harmful radiation

decay
verb [ I/T ] us /dɪˈkeɪ/
decaying
adjective [ not gradable ] us /dɪˈkeɪ·ɪŋ/

Empty lots stand next to abandoned, decaying buildings.

(Definition of “decay” from the Cambridge Academic Content Dictionary © Cambridge University Press)