Definitions

1. adjective

not capable of moving or changing; not active or effective

“The inert gas in the container did not react with the surrounding environment.”

2. noun

a substance that does not react with other substances

“The inert gas was used as a propellant in the rocket engine.”

3. noun

a part of a machine or device that does not move or change position

“The inert part of the gear system was lubricated to reduce friction.”