A more thorough explanation:

A weak mark is a type of trademark that is descriptive or suggestive of the product or service it represents. This means that the mark does not have a strong association with the source of the product or service, and is therefore less distinctive and less likely to be protected under trademark law.

For example, the mark "Apple" for computers and electronics is a strong trademark because it is arbitrary and has no direct association with the product. However, the mark "Fresh" for a grocery store is a weak trademark because it is descriptive of the products being sold and does not have a strong association with the store itself.

Weak marks may still be protected under trademark law if they have acquired secondary meaning, which means that the mark has become associated with the source of the product or service through extensive use and marketing.