What term refers to the amount of matter in an object?

The term that refers to the amount of matter in an object is mass. Mass is a fundamental property of matter and is measured in units such as grams or kilograms. It quantifies how much substance is present in an object, regardless of its location or the effects of gravity.

To provide context for the other options: weight is often confused with mass; however, weight is the force exerted by gravity on an object and depends on the object's mass and the gravitational pull of the environment. Volume measures the amount of space an object occupies, which is not directly related to the quantity of matter present. Density, on the other hand, is defined as mass per unit volume, showcasing a relationship between mass and volume but not representing the amount of matter itself. Hence, mass is the most accurate term to describe the quantity of matter in an object.