decay
/dɪˈkeɪ/ (bre, ipa) · /dɪˈkeɪ/ (ame, ipa) · /di-ˈkā/ (ame, mw)
decay — verb
- decaypresent simple I / you / we / they
- decays3rd person singular
- decaying-ing form
- decayedpast simple
1. to become gradually weaker, more damaged, or less effective over time, or to cau
to become gradually weaker, more damaged, or less effective over time, or to cause this to happen. For example, a tooth decays when acid breaks down the enamel, a building decays when no one repairs it, or a relationship decays when trust erodes.
The wooden fence had begun to decay after years of rain and sun.
intransitive: [material] + decay after + [conditions]
If you do not brush your teeth every day, they will decay and hurt.
Sugary drinks can decay the enamel on your teeth over time.
The Roman Empire slowly decayed as its borders came under attack.
A marriage can decay when both partners stop listening to each other.
- rot
more specific to organic material breaking down, often with a smell
- deteriorate
more formal; can apply to abilities, conditions, or situations
- decompose
technical term for organic matter breaking down chemically
- decline
focuses on losing quality or strength rather than physical damage
文法句型
decay (intransitive): [subject] decays
decay + noun phrase (transitive): [agent] decays [object]
用法筆記
Commonly used without a direct object (intransitive). The transitive form ('Something decays something else') is rarer and typically used for teeth or organic matter.
常見錯誤
2. when a radioactive substance such as uranium or carbon-14 changes naturally into
when a radioactive substance such as uranium or carbon-14 changes naturally into another substance by releasing radiation from its atoms
Uranium-238 decays into thorium-234 by releasing an alpha particle.
[element] + decays into + [element]
Scientists measure how fast a radioactive material decays to find out how old something is.
Carbon-14 decays at a steady rate, which makes it useful for dating old bones.
When a nucleus decays, it gives off energy in the form of radiation.
- break down
less technical, describes the process in everyday language
- disintegrate
suggests the nucleus breaking apart into smaller pieces
文法句型
decay + into + noun phrase (resulting element)
用法筆記
Subject is always a radioactive element or isotope. The rate of decay is constant for each substance and cannot be changed by outside conditions.
常見錯誤
decay — noun
1. the process by which something becomes gradually damaged, weaker, or destroyed,
the process by which something becomes gradually damaged, weaker, or destroyed, either from natural causes or from lack of care. This can apply to teeth, buildings, plants, societies, or moral standards.
The old house was in decay, with holes in the roof and broken windows.
collocation: in a state of decay
Tooth decay is one of the most common health problems for children around the world.
common compound: tooth decay
The city's economic decay began when the main factory closed down.
The abandoned hospital showed signs of decay — peeling paint and rusty beds.
- rot
stronger emphasis on organic decomposition and smell
- decomposition
scientific term for the chemical breakdown of matter
- decline
focuses on loss of quality or strength, often for systems or societies
- deterioration
more formal, gradual worsening of condition
- growth
for plants, societies, or economies
- restoration
bringing something back to its original condition
文法句型
[be] in a state of decay
[the] decay of + [noun]
用法筆記
Frequently paired with 'fall into' or 'in a state of'. Unlike 'rot', 'decay' can describe both physical things and abstract ideas (e.g. moral decay, urban decay).
常見錯誤
2. the natural process in which a radioactive material releases energy and changes
the natural process in which a radioactive material releases energy and changes into a different form or element
Radioactive decay releases energy that nuclear power plants use to make electricity.
The rate of decay for each radioactive element stays the same at any temperature.
collocation: rate of decay
Geologists use radioactive decay to measure the age of ancient rocks and fossils.
Nuclear decay cannot be controlled or stopped once it begins.
- nuclear decay
more specific to changes in the atomic nucleus
- radioactive disintegration
formal technical term
文法句型
radioactive decay of + [element]
rate of decay
用法筆記
Used in physics, chemistry, and geology. 'Decay' in this sense is always uncountable and refers to a measurable, predictable process.