Scientific meaning: Inertia is described as resistance to alteration of its condition of movement, mobile or inert. Meaning that if an object is moving at 100kmh, it would require a force of greater than that to move it. If the object is immobile, it will require a force sufficient to move its mass.
Common usage, applied to people: Inertia means a state of idleness, or unchanging condition, usually a derogatory expression.
Examples of Inertia:
The rock traveled by inertia down the hill, too big to be stopped by obstacles.|
Some people live in a state of inertia, where nothing ever alters their mindsets or perspectives.