An ejectable is a physical item, such as a lens cover, deployment mechanism, or spent stage, that a vehicle intentionally jettisons. Spacecraft designers must carefully track the trajectory of ejectables to ensure they do not strike the main vehicle or become hazardous orbital debris. In aviation, it can refer to drop tanks or emergency egress systems.
Heard on the job
The star tracker cover is a standard ejectable, and telemetry confirms it cleared the vehicle.