What is the alternative term for bulk modulus?

The term that serves as the alternative for bulk modulus is indeed stiffness. Bulk modulus is a measure of a material's resistance to uniform compression, describing how incompressible a substance is. It quantifies the relationship between volumetric strain and the applied pressure, effectively expressing the material's stiffness with respect to volumetric deformation.

In a physical sense, stiffness indicates how much a material will deform under a given applied force, which corresponds directly with the concept of bulk modulus. A material that has a high bulk modulus is considered very stiff, as it requires a significant amount of pressure to achieve a small change in volume. Thus, recognizing the connection between these concepts is crucial in understanding material properties in sonography and related fields.

The other terms such as density, compressibility, and elasticity are relevant to material properties but do not function as synonymous terms for bulk modulus. Density refers to mass per unit volume, compressibility describes how much a substance deforms under pressure inversely to bulk modulus, and elasticity relates to the ability of a material to return to its original shape after deformation, which while connected, defines different aspects of material behavior compared to stiffness.