A mark is considered merely descriptive if it describes an ingredient, quality, characteristic, function, feature, purpose or use of the specified goods or services. If a mark is merely descriptive or deceptively misdescriptive of the goods or services to which it relates, the mark will be refused registration on the Principal Register under §2(e)(1) of the Trademark Act, 15 U.S.C. §1052(e)(1).
Examples of descriptive marks include: MEDICAL GUIDE for website services featuring medical guides, DENIM for jeans, and SPICY SAUCE for salsa.
— see TMEP §1209 for more info