sea level

American  

noun

1. the horizontal plane or level corresponding to the surface of the sea at mean level between high and low tide.

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sea level British  

noun

1. the level of the surface of the sea with respect to the land, taken to be the mean level between high and low tide, and used as a standard base for measuring heights and depths

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sea level Scientific  

1. The level of the ocean's surface. Sea level at a particular location changes regularly with the tides and irregularly due to conditions such as wind and currents. Other factors that contribute to such fluctuation include water temperature and salinity, air pressure, seasonal changes, the amount of stream runoff, and the amount of water that is stored as ice or snow.

2. ◆ The reference point used as a standard for determining terrestrial and atmospheric elevation or ocean depths is called the mean sea level and is calculated as the average of hourly tide levels measured by mechanical tide gauges over extended periods of time.

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Etymology

Origin of sea level

First recorded in 1800–10

Example Sentences

Last year, the global mean sea level was around 11 centimetres higher than when satellite altimetry records began in 1993.

From Barron's • Mar. 23, 2026

South Africa, at Johannesburg's Ellis Park - 1,753m above sea level - is England's next, imposing task.

From BBC • Mar. 14, 2026

Between 1901 and 2018, the global average sea level rose by about 20 centimetres.

From Barron's • Mar. 11, 2026

The Amundsen Sea accounts for most of the sea level rise driven by Antarctic melting.

From Science Daily • Feb. 28, 2026

A forlorn plateau of bulletproof ice and windswept boulders 26,000 feet above sea level, it occupies a broad notch between the upper ramparts of Lhotse and Everest.

From "Into Thin Air" by Jon Krakauer

Related Words

• water level