Earth

Earth or ground has many meaning in electronics. First, it is a point in an electrical circuit from which voltage is measured.

Second, it is the name of the wire used in plugs normally coloured green and yellow. Third, when electricity is connected to the ground it helps to control the voltage. Finally, the word earth or ground is common in electronic applications in vehicles such as cars, ships or aircraft. And, also in spaceships that talk about a "ground" connection without being on the Earth.