Inertial (adjective)

1. Resistant to motion or change; tending to remain in a state of rest or uniform motion.
2. Relating to the state of an object in motion or at rest.

Origin:

From the latin word "inerte" meaning inactive or sluggish.

Examples:

1. An inertial navigation system uses accelerometers to measure the velocity and orientation of a moving object.
2. The rocket's inertial guidance system helped keep it on course during launch.
3. The child was inertial and refused to leave the house.
4. The inertial mass of an object is a measure of its resistance to acceleration.
5. The inertial frames of reference are frames of reference in which the laws of physics take the same form as in the non-accelerating frame.