What is it called when you use a brand name to describe an item?

Using a brand name to describe a general item is known as "genericide." This occurs when a trademarked brand name becomes so well-known that it is used as a generic term for similar products, regardless of the manufacturer. Examples include "Kleenex" for tissues or "Band-Aid" for adhesive bandages. While this can signify a brand's success, it can also lead to the loss of trademark protection.