# Poisson's ratio

### or Poisson ratio

- the ratio, in an elastic body under longitudinal stress, of the transverse strain to the longitudinal strain.

## Origin of Poisson's ratio^{}

First recorded in 1925–30; see origin at Poisson distribution

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# Poisson's ratio

- a measure of the elastic properties of a material expressed as the ratio of the fractional contraction in breadth to the fractional increase in length when the material is stretchedSymbol: μ, ν

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