# decay

/dɪˈkeɪ/ (US) · /dɪkˈeɪ/ (UK)

Source: https://englishreference.com/word/decay
Updated: 2026-08-15

## Senses

### 1. rotting matter

noun · CEFR B2

the natural process of organic things, like food or wood, breaking down and rotting.

For teachers: the process or result of organic matter being decomposed, typically by microbial or fungal action.

- The old log was covered in moss and showed signs of advanced decay.
- Forensic investigators used the rate of organic decay to estimate the time of death with surprising accuracy.

### 2. decline in quality

noun · CEFR B2

a gradual loss of strength, beauty, or health in a person, building, or society.

For teachers: a gradual deterioration in condition, status, quality, or strength.

- The mayor promised to fix the urban decay in the city's oldest neighbourhoods.
- The historian argued that the empire's collapse was caused by centuries of internal moral and economic decay.

### 3. radioactive process

noun · CEFR C1 · Technical

the process where an atom loses energy by releasing radiation.

For teachers: the spontaneous transformation of an unstable atomic nucleus into a lighter one, accompanied by the emission of radiation.

- Scientists measured the radioactive decay of the carbon to find the age of the bone.
- The half-life of an isotope is defined as the time required for half of the nuclei in a sample to undergo radioactive decay.

### 4. to rot

verb · CEFR B2

to break down naturally or go bad.

For teachers: to undergo decomposition; to rot through natural chemical or biological processes.

- Sugar can cause your teeth to decay if you do not brush them regularly.
- Without proper ventilation, the wooden beams in the basement will eventually decay due to the high humidity.

### 5. to get worse

verb · CEFR B2

to slowly become weaker or lose quality.

For teachers: to decline gradually from a sound or prosperous condition to a lower state.

- The relationship began to decay after they stopped talking to each other.
- The abandoned mansion was left to decay, its once-grand ballroom now filled with dust and shadows.

### 6. programming

verb · CEFR C2 · Technical

when a list of data changes into a simpler pointer in computer code.

For teachers: the process by which an array loses its type and dimensions, being reduced to a pointer, typically when passed to a function.

- In C++, you must be careful when an array decays into a pointer.
- The developer noted that the array would decay upon being passed to the legacy function, losing its size information in the process.

Usage: The verb is intransitive in this context.

## Examples

- The old wooden fence shows signs of decay.
- The dentist explained that sugar is the primary cause of tooth decay in young children.
- The abandoned factory stood as a monument to urban decay, its rusted beams and shattered windows reflecting the economic decline of the surrounding neighborhood.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.