<P> Young's modulus, also known as the elastic modulus, is a measure of the stiffness of a solid material . It is a mechanical property of linear elastic solid materials . It defines the relationship between stress (force per unit area) and strain (proportional deformation) in a material . Young's modulus is named after the 19th - century British scientist Thomas Young . However, the concept was developed in 1727 by Leonhard Euler, and the first experiments that used the concept of Young's modulus in its current form were performed by the Italian scientist Giordano Riccati in 1782, pre-dating Young's work by 25 years . The term modulus is the diminutive of the Latin term modus which means measure . </P> <P> A solid material will deform when a load is applied to it . If it returns to its original shape after the load is removed, this is called elastic deformation . In the range where the ratio between load and deformation remains constant, the stress - strain curve is linear . Not many materials are linear and elastic beyond a small amount of deformation . A stiff material needs more force to deform compared to a soft material, and an infinite force would be needed to deform a perfectly rigid material, implying that it would have an infinite Young's modulus . Although such a material cannot exist, a material with a very high Young's modulus can be approximated as rigid . </P>

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