n.1 Physics a property of matter by which it continues in its existing state of rest or uniform motion in a straight line, unless that state is changed by an external force.
2 inertness, sloth.
Phrases and idioms:
inertia reel a reel device which allows a vehicle seat belt to unwind freely but which locks under force of impact or rapid deceleration. inertia selling the sending of unsolicited goods in the hope of making a sale.
Derivatives:
inertial adj. inertialess adj.
Etymology: L (as INERT)