What is the stress term called which is a measure of the stiffness or resistance to deflection?

The term that describes the stiffness or resistance to deflection of a material is known as the Modulus of Elasticity. This parameter quantifies how much a material will deform under stress; specifically, it defines the relationship between stress (force per unit area) and strain (deformation) within the elastic limit of that material. A higher Modulus of Elasticity indicates that a material is stiffer and will experience less deformation when subjected to a given load. This concept is crucial in various fields, such as structural engineering and materials science, as it helps in the selection of materials for construction and manufacturing processes based on their ability to withstand applied forces without permanent deformation.

The other options refer to different properties of materials: Shear strength is related to the maximum shear stress a material can withstand; Tensile strength measures the resistance of a material to breaking under tension; and Flexural modulus specifically measures stiffness during bending. However, the Modulus of Elasticity is the broadest term used to express resistance to deformation in response to applied stress.