One of the requirements for federal protection is that the trademark be used in interstate commerce. Otherwise, the mark can be protected only under state law. Trademarks can be placed into 1 of 4 categories. Arbitrary marks are terms that do not convey any description of the characteristic or the nature of the product. Arbitrary marks are usually coined marks.
Suggestive marks require imagination to determine the relationship between the product and the mark.
Merely descriptive marks are terms that describe the product itself, such as the product's ingredient or a characteristic of the product. In other words, you will need to show that the primary significance of the term in the minds of the consuming public is not the product itself but your company. A generic mark is a term that the public perceives as primarily describing the product. This is a term that is describing a particular type of pain reliever. However, this term does not distinguish the manufacturer of the product.