A genericized trademark is simply a brand name that has become the common name of the product. A trademark is supposed to be a “badge of origin”. That is to say, the essential function of a trademark is to distinguish the goods or services of one business from the goods or services of other businesses. It enables consumers to identify where a product comes from. The trademark tells you who made or supplied that product.
Sometimes, however, a trademark can cease to perform this function and instead it becomes the actual generic name of the product itself. This may happen for a variety of reasons. For example, because the owner of the trademark has a monopoly in that particular product, or because the trademark has been carelessly used by the owner, or because the product or brand has simply been too successful.
There are many examples of trademarks that have become generic. One of the most famous examples, is the mark HOOVER, which became the common name for a vacuum cleaner. The mark “Linoleum” was ruled as generic following a court case trademark infringement in 1878. It was probably the first trademark to become a generic term. Likewise, the trademark BIRO, which became the generic name for a plastic disposable ball-point pen. Other examples include, ASPIRIN, ESCALATOR, and THERMOS.
There are a large number of legally protected trademarks, which are sometimes used by consumers in a generic sense. These trademarks are in danger of being declared generic. Examples include Jacuzzi, and Xerox.