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The property of a body to resist a change in its state of rest or of uniform motion.

Other Definition: The property of matter that causes it to resist any change in its state of rest or of uniform motion. There are three kinds of inertia- inertia of rest ; inertia of motion and inertia of direction. The mass of a body is a measure of its inertia.

Other Definition: tendency of object not to change its motion.

Other Definition: The property of matter that opposes any change in its state of motion.

Other Definition: The tendency of an object to remain at a constant velocity ; or its resistance to being accelerated. Newton's First Law is alternatively called the Law of Inertia because it describes this tendency