Before revision: Idle speed, sometimes simply called "idle", is the rotational speed an engine runs at when the engine is idling, that is when the engine is uncoupled from the drivetrain and the throttle pedal is not depressed .
After revision: Idle speed, sometimes simply called "idle", is the rotational speed an engine runs at when the engine is idling, that is when the engine is uncoupled from the drivetrain and the throttle is not activated .