1. Physics The tendency of a body at rest to remain at rest or of a body in straight line motion to stay in motion in a straight line unless acted on by an outside force; the resistance of a body to changes in momentum.
2. Resistance or disinclination to motion, action, or change: an entrenched bureaucracy's inertia.
[Latin, idleness, from iners, inert-, inert; see INERT.]
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