A trademark is considered to be descriptive if it describes the product or service, or if it describes a characteristic, purpose, function, quality or use of the product or service. Under trademark law, a mark that is “merely descriptive” is not immediately eligible for trademark registration on the principal trademark register. (A mark that is merely descriptive may be eligible for registration on the Supplemental Trademark Register.) This law is logical, as marks that are merely descriptive are needed by competitors in the marketplace to describe their products or services, and the law frowns on taking terms out of commerce that competitors need to compete effectively. In a determination of whether a mark is merely descriptive, one or more words cannot be taken out of context. Instead, the entire mark, as a whole must be evaluated for descriptiveness.

A mark that is merely descriptive of the product or service may become eligible for trademark registration if it acquires distinctiveness. Acquired distinctiveness (so-called secondary meaning) is developed through use of a trademark over time in conjunction with the product or service. As such, the public now perceives the mark as identifying the product or service from a particular source and no longer as descriptive of the product or service. The United States Patent and Trademark Office considers continuous use for five years of a descriptive mark in commerce in conjunction with a product or service as prima facie evidence of acquired distinctiveness.