Lost ground is a term used to describe land that has been damaged or destroyed due to natural or human-made causes. Slid (4 letters) is a term used to describe the movement of land due to gravity, usually caused by an earthquake or landslide. Eroded (6 letters) is a term used to describe the gradual wearing away of land due to wind, water, or other natural forces. Together, these two terms describe the process of land being lost due to natural or human-made causes.