Poisson's ratio

American  

Or Poisson ratio

noun

Physics.

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

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Poisson's ratio British  

noun

1.  μ.   ν.  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 stretched

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Etymology

Origin of Poisson's ratio

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

Example Sentences

The breakthrough centered on a property called Poisson's ratio, which describes how materials change shape when stretched.

From Science Daily • May 13, 2026

By pairing in-situ sound velocity measurements with advanced molecular dynamics simulations, the team detected a dramatic loss of shear wave speed and a sharp increase in Poisson's ratio.

From Science Daily • Dec. 10, 2025

Most materials have a positive Poisson's ratio, which means squeezing them in one direction will make them wider and/or thicker in other directions.

From Science Daily • Jun. 4, 2024

The behavior of elastic materials is partially described by Poisson's ratio, which explains how the material changes shape when you stretch or squeeze it in one direction.

From Science Daily • Jun. 4, 2024

The Poisson’s ratio depends upon the direction of the contracted lateral filaments as well as upon that of the longitudinal extended ones.

From Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 2 "Ehud" to "Electroscope" by Various