The word mech is used in alot of sci-fi works. but once you put the ' in front of it, it is officialy a Battletech (product of FASA) vehicle. A 'Mech (short for BattleMech) is a humanoid shaped, walking tank fueled by miniature fusion plants. They range from 10 to 100 tons. Their height can range from 10 to 15 meters.