Famous Marks
Some trademarks are so well known, that they are regarded as famous marks. With a famous mark, there is no need to show a likelihood of confusion. Others simply can't use or register the famous mark to identify even unrelated products. So one can't use the term NIKE to sell oranges, even if there are no NIKE brand oranges on the market and no likelihood of confusion. If someone does use a famous mark, they can be sued for blurring and tarnishment. Famous marks can be used by others under the nominative fair use doctrine.