<p><strong>Noun</strong></p><ul><li>Chiefly British. The ridge or crest line dividing two drainage areas; water parting; divide.</li><li>The region or area drained by a river, stream, etc.; drainage area.</li><li>Architecture. wash (def 45).</li><li>An important point of division or transition between two phases, conditions, etc.: The treaty to ban war in space may prove to be one of history's great watersheds.</li></ul><p><strong>Adjective</strong></p><ul><li>Constituting a watershed: a watershed area; a watershed case.</li></ul><p><strong>End of Response</strong></p>