How would you define "inertia"?

Answer 1

Inertia is the tendency of an object to resist changes in its state of motion. It is a property of matter that relates to an object’s mass – the more massive an object, the greater its inertia, and the harder it is to change its motion. Inertia is described by Newton’s first law of motion which states that an object at rest will remain at rest, and an object in motion will continue in motion in a straight line with a constant speed, unless acted upon by an external force.