The term 'wearing away gradually' can be described as 'eroding' which is a 7 letter word. Erosion is the process of wearing away of the surface of the earth due to natural forces such as wind, water, and ice. It can also be caused by human activities such as deforestation and overgrazing. Erosion can cause soil loss, land degradation, and even desertification. Erosion can also lead to the destruction of habitats and the displacement of wildlife.