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

Described as a “legacy estate,” the home sits 2,200 feet above sea level on Haleakala’s western slope, which means that the “unique residence enjoys the best of the mild upcountry climate.”

From MarketWatch • Apr. 28, 2026

"The highest point above sea level in Kiribati - unless you climb a coconut tree - is two metres. No water, no land, no resources other than fish."

From BBC • Apr. 26, 2026

Planters started anew in central Florida, in Polk County and its surroundings, what’s known as the Ridge, the highest part of Florida, and the only part that was never below sea level, historically.

From Slate • Apr. 20, 2026

Sixty miles from Julian, I turn onto Bannister Road and bump north along a gravel track for three miles into the basin, to a parking lot 164 feet below sea level.

From Los Angeles Times • Apr. 7, 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