watershed

Merriam-Webster's Word of the Day for September 17, 2026 is: watershed • WAW-ter-shed  • noun Watershed, used figuratively, refers to a crucial dividing point, line, or factor. Used literally, the word may refer to a ridge from which rivers drain on either side, or to the area of land that includes a particular river or lake and all the rivers, streams, etc. that flow into it. : a crucial dividing point, line, or factor // The protests marked a watershed in the nation’s history. // The Continental Divide is the most well known watershed in the United States. See the entry > Examples: “For thousands of years, elk would have accounted for the second largest amount of meat in the diets of many eastern peoples, after the ubiquitous whitetail deer. Not only were the animals present in the East; for thousands of years they sustained human life and were integral to Indigenous material and spiritual culture. Although they were great and skilled hunters, Native Americans in the East rarely killed all of the elk or all of the deer in an entire watershed.” — Andrew Moore, Beasts of the East: The Fall and Rise of America’s Eastern Wilderness, 2026 Did you know? Opinion on the literal geographic meaning of watershed is divided. On one side of the debate are those who think the word can only refer to a ridge of land separating rivers and streams flowing in one direction from those flowing in the opposite direction. That’s the term’s original meaning, one probably borrowed in the translation of the German Wasserscheide. On the other side of the argument are those who think watershed can also apply to the area through which such divided water flows. The latter sense is now far more common in America, but most speakers have apparently decided to leave the quarrel to hydrologists and geographers, choosing to limit their use of watershed to its figurative “turning point” sense.