Trademark dilution is making a famous mark weaker.
Trademark dilution can occur "by blurring" or "by tarnishment."
A dilution action only applies to purely commercial speech.
Trademark dilution by blurring is when a "famous mark" loses some of its distinctiveness because of the use of a similar mark, regardless of what for.
There are six factors used to determine dilution by blurring:
Trademark dilution by tarnishment is when a "famous mark" has its reputation hurt because of a similarly named product of poor quality or unwholesome context.
There is no hard line for what a famous mark is, but it has to be really famous. Usually around 70% recognition among the general population is required.
To determine whether a mark is famous, four factors are used: