Mass

Mass is a certain concept used to describe the general weight of matter. Weight is the product of mass and the gravitational constant. The units used to denote mass are kilograms.

Definition of Mass
If the same force is applied to two different objects (m(1) and m(2)) and they experience different accelerations (a(1) and a(2)), then the division of m(1) over m(2) would equal the division of a(1) over a(2);

m(1)/m(2) = a(1)/a(2)