The definition of inbound is something that moves inward. An example of inbound is the freeway that goes toward the city center. 1  traveling or going inward.  Basketball inbounds.
Mass is a measurement of how much matter is in an object. Mass is a combination of the total number of atoms, the density of the atoms, and the type of atoms in an object. How to Measure Mass.
Many scientists literally define mass as how much stuff is there.. Mass is different than weight. Weight depends on gravitational pull. However, mass (which is measured by a balance), is the same no matter what the gravitational force.