verb
decay
dih-KAY
verb
1
To rot or gradually break down, especially of organic matter.
"The fallen leaves slowly decayed into the soil."
"Without treatment, the tooth will continue to decay."
2
To decline gradually in quality, strength, or condition.
"The old empire's power decayed over several centuries."
noun
1
The process or result of rotting or gradual deterioration.
"The building showed signs of decay after years of neglect."
"Tooth decay is largely preventable with good brushing habits."
2
In physics, the process by which an unstable atomic nucleus or particle breaks down over time.
"Scientists measured the radioactive decay of the isotope."
How to Use Decay
Learner’s notesIn plain EnglishTo rot or gradually get worse — used for teeth, buildings, empires, and even radioactive atoms.
Common pairings
tooth decay
radioactive decay
fall into decay
Word Forms
decayed past tense, decays plural, decays singular
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Etymology
From Anglo-Norman decaeir, ultimately from Latin dē- ("down, away") + cadere ("to fall") — the same root as "decadent" and "decadence."