1. Anat.a cord or funicle connecting the embryo or fetus with the placenta of the mother and transporting nourishment from the mother and wastes from the fetus.
2. any electrical, fuel, or other cable or connection for servicing, operating, or testing equipment, as in a rocket or missile, that is disconnected from the equipment at completion.
3. Aerospace Slang.a strong lifeline by which an astronaut on a spacewalk is connected to the vehicle and supplied with air, a communication system, etc.