What Is the Scientific Definition of "weight"?

In scientific terms, weight is a force and uses the newton as its unit. The conventional definition of weight is actually mass, which is the amount of matter something contains. Weight and mass are directly proportionate because the acceleration of gravity stays constant in the formula for weight. The gravity on Earth remains at a constant 9.8 meters per second per second. As the amount of matter in an object increases, the force the acceleration of gravity exerts on an object increases.