high-water mark

American  

[hahy-waw-ter, -wot-er] / ˈhaɪˈwɔ tər, -ˈwɒt ər /

noun

1. a mark showing the highest level reached by a body of water.

2. the highest point of anything; acme.

   Her speech was the high-water mark of the conference.

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high-water mark British  

noun

1. 1. the level reached by sea water at high tide or by other stretches of water in flood

   2. the mark indicating this level

2. the highest point

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high-water mark Idioms  

1. The peak of something, especially an achievement. For example, This composition is the high-water mark of his entire output. This expression alludes to the highest mark left on shore by the tide. [Mid-1800s]

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Etymology

Origin of high-water mark

First recorded in 1545–55

Example Sentences

As for domestic policy, the high-water mark of federal government power previously was coincidently during the tenure of TR’s distant cousin, Franklin Delano Roosevelt, in the New Deal.

From Barron's • Jan. 23, 2026

In the 2025 tests, the L.A. school system surpassed its achievement levels of 2018-19, L.A.’s previous high-water mark under the current testing system.

From Los Angeles Times • Jan. 15, 2026

Wall Street has been throwing in some strong stock-market bets for 2026, but the high-water mark just got higher.

From MarketWatch • Nov. 26, 2025

They racked up some electoral wins, and at their high-water mark received 7.1% of the vote in 1989 European Parliament elections in West Germany.

From The Wall Street Journal • Nov. 6, 2025

When the counterfeit Beast was perfected, the knights took it away and hid it in a cave at the foot of the cliffs, above high-water mark.

From "The Once and Future King" by T. H. White

Related Words

• apex
• apogee
• upper limit