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.
Definition of mass for Students. 1  1 : a large quantity or number A great mass of people pushed through the gate. 2  2 : an amount of something that holds or clings together a mass of clouds. 3  3 : large size : bulk an elephant's huge mass. 4  4 : the principal part : main body The great mass of voters supported change.