low-water mark

noun

1. the lowest point reached by a low tide.
2. something indicating the bottom of a decline.
3. the lowest or least admirable level:

   the low-water mark of political chicanery.

low-water mark

noun

1. the level reached by seawater at low tide or by other stretches of water at their lowest level
2. the lowest point or level; nadir

Word History and Origins

Origin of low-water mark¹

First recorded in 1520–30