The term 'tending to wear down' can be summarized by two crossword solutions: 'EROSIVE' and 'erodent'. EROSIVE refers to the process of erosion, which is the gradual wearing away of the surface of the earth due to the action of wind, water, or other natural forces. Erodent, on the other hand, refers to something that causes erosion, such as a river or ocean current. Both terms are used to describe the process of wearing down or eroding something over time.