What does the term 'elasticity' refer to in physical terms?

The term 'elasticity' in physical terms refers to the ability of a material to resume its normal shape after being stretched or compressed. This property is essential in many materials, as it determines how they respond to forces applied to them. When a material is stretched or compressed within its elastic limits, it will return to its original shape once the force is removed. This characteristic is critical in various applications, including engineering, physics, and materials science, where the performance and durability of materials are evaluated based on their elastic properties.

The other options do not accurately define elasticity: the capability of a material to fracture pertains to its brittleness rather than its elastic properties. The ability to passively move without resistance relates more to concepts of mobility and fluidity rather than elasticity itself. Measuring flexibility in joints is specific to anatomical terms and biomechanics and does not encompass the broader definition of elasticity in materials. Thus, the option that refers to the ability to resume normal shape after being stretched or compressed is the most precise representation of the concept of elasticity.