Merriam-Webster's Word of the Day for September 17, 2026 is watershed. This word has both a literal and a figurative meaning. Literally, a watershed can refer to a ridge that divides drainage areas. It can also refer to the entire land area that drains into a river or lake. Many Native American communities historically relied on elk and deer within their watersheds. The figurative meaning of watershed is a crucial dividing point, line, or factor. This sense signifies a moment of significant change or turning point. For instance, protests can mark a watershed in a nation's history. The Continental Divide is a well-known example of a literal watershed in the United States. There is debate among experts regarding the precise definition of the literal geographic meaning. However, most people commonly use watershed in its figurative sense to denote a turning point.