seawater

American  

[see-waw-ter, -wot-er] / ˈsiˌwɔ tər, -ˌwɒt ər /

noun

1. the salt water in or from the sea.

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seawater Scientific  

/ sē′wô′tər /

1. Salt water, normally with a salinity of 35 parts per thousand (3.5%), in or coming from the sea or ocean. Although seawater contains more than 70 elements, most seawater salts are ions of six major elements: chloride, sodium, sulfate, magnesium, calcium, and potassium. The major sources of these salts are underwater volcanic eruptions, chemical reactions involving volcanic matter, and chemical weathering of rocks on the coasts. Seawater is believed to have had the same salinity for billions of years.

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Etymology

Origin of seawater

before 1000; Middle English see water, Old English sǣwæter; see sea, water

Example Sentences

In the year following the Palisades and Eaton fires, levels of harmful metals like lead in coastal sand and seawater have remained far below California’s limits for safe drinking water and the U.S.

From Los Angeles Times • Mar. 20, 2026

"The ship can produce fresh water by desalinating seawater, but that becomes difficult if we are not sailing," he says.

From BBC • Mar. 12, 2026

The loss of polar ice sheets is the main driver of sea-level rise, ahead of melting mountain glaciers and the thermal expansion of seawater, which occurs as the oceans warm due to global heating.

From Barron's • Mar. 11, 2026

In regions where gravity is weaker, seawater tends to flow toward areas where the pull is stronger.

From Science Daily • Mar. 7, 2026

There are now so many jellyfish that power plants around the world have been shut down when hundreds of thousands of the creatures have clogged their seawater cooling systems.

From "The Thing About Jellyfish" by Ali Benjamin