What is the term for resistance of a material to compression?

• A. Stiffness
• B. Sound
• C. Spatial
• D. Temporal

Answer: (A)

Stiffness is the measure of how much a material resists being deformed when a compressive force is applied. A stiffer material deforms less under the same amount of compression, while a more compliant material deforms more. That resistance to compression is exactly what stiffness describes.

The other terms don’t fit because sound refers to wave propagation, while spatial and temporal describe dimensions or timing rather than a material’s resistance to deformation. In ultrasound contexts, stiffness helps explain how tissues respond to pressure and underpins concepts like how easily they compress under palpation or during elastography.