wa·ter·shed (wôtər-shĕd′, wŏtər-)
1. The entire region draining into a river, river system, or other body of water: a list of reptiles found in the watershed. Also called basin, drainage basin.
2. A ridge of high land dividing two areas that are drained by different river systems. Also called divide, water parting.
3. A critical point that marks a division or a change of course; a turning point: "a watershed in modern American history, a time that ... forever changed American social attitudes" (Robert Reinhold).
[Probably translation of German Wasserscheide, water parting, border between watersheds : Wasser, water + Scheide, divide, parting.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.