# Definition of pi

### Definitions

nounWord forms: plural pis

1. the 16th letter in the Greek alphabet (Π, π), a consonant, transliterated as p

2. mathematics a transcendental number, fundamental to mathematics, that is the ratio of the circumference of a circle to its diameter. Approximate value: 3.141 592…; symbol: π

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### Word origin of 'pi'

C18 (mathematical use): representing the first letter of Greek periphereia periphery### Definitions

verbWord forms: pies, piing, pied, pies, pieing or pied (transitive)

4. to mix up

Collins English Dictionary. Copyright © Harper Collins Publishers

### Word origin of 'pi'

C17: of uncertain origin### Definitions

adjective

Collins English Dictionary. Copyright © Harper Collins Publishers

## PI

### Definitions

Collins English Dictionary. Copyright © Harper Collins Publishers

### Definitions

number

Pi is a number, approximately 3.142, which is equal to the distance round a circle divided by its width. It is usually represented by the Greek letter π.

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## Source

*Definition of*Collins English Dictionary

**pi**from the
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