What term describes the material upon which gravity acts?

The term that describes the material upon which gravity acts is mass. Mass is a fundamental property of matter that quantifies the amount of substance in an object or material, and it is this property that interacts with the force of gravity. Gravity pulls on mass, which is why heavier objects (those with greater mass) experience a stronger gravitational pull than lighter ones.

In the context of this question, weight, while related to mass, refers specifically to the force exerted by gravity on that mass and varies depending on the gravitational field strength, such as on different celestial bodies. Volume refers to the amount of space an object occupies, and density is the ratio of mass to volume. While these terms are essential in understanding the properties of materials, only mass directly describes the material that gravity acts upon.