# prime

/ˈpɹaɪm/ (US) · /pɹˈaɪm/ (UK)

Source: https://englishreference.com/word/prime
Updated: 2026-06-19

## Senses

### 1. best or most important

adjective · CEFR B2

of the best quality or the most important.

For teachers: first in importance, degree, or quality; often used to describe the most relevant or excellent example of something.

- The hotel is in a prime location right next to the city's main square.
- The property's prime location in the financial district ensures that its market value remains high despite economic fluctuations.

### 2. mathematics

adjective · CEFR B2 · Technical

describes a number that can only be divided by itself and the number one.

For teachers: relating to a positive integer greater than one that has no positive integer divisors other than one and itself.

- Seven is a prime number because you cannot divide it by two, three, or four.
- Encryption algorithms often rely on the mathematical difficulty of factoring the product of two large prime numbers.

### 3. the best period of life

noun · CEFR B2

the time in your life when you are strongest, most successful, or most beautiful.

For teachers: the state or time of greatest vigour, strength, or success in a person's life or a thing's existence.

- The athlete was in his prime when he won the gold medal.
- Many critics argue that the painter reached her artistic prime during her years in Paris, before her style became more commercial.

### 5. to apply a base coat

verb · CEFR B2 · Technical

to put a first layer of special paint on a surface before the main paint.

For teachers: to apply a coat of primer to a surface to prepare it for a finished layer of paint or varnish.

- You need to prime the wooden door before you paint it blue.
- Failure to prime the metal surface correctly will result in the topcoat peeling off within a few months of exposure to the elements.

### 6. to make a pump or engine ready

verb · CEFR C1 · Technical

to put liquid into a pump or engine so that it can start working.

For teachers: to pour liquid into a pump or to supply fuel to an engine to prepare it for operation.

- He had to prime the old water pump before any water would come out.
- The mechanic explained that you must prime the fuel system manually if the vehicle has been sitting idle for several years.

## Examples

- The athlete is currently in the prime of his career.
- Many people believe that they reach their intellectual prime during their thirties or early forties.
- The historic building was restored to its former glory, reflecting the architectural grandeur it possessed during its Victorian prime.

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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.