underwater

American  

[uhn-der-waw-ter, -wot-er] / ˈʌn dərˈwɔ tər, -ˈwɒt ər /

adjective

1. existing or occurring under water.

2. designed to be used under water.

3. located below a ship's waterline.

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adverb

1. beneath the water.

   to travel underwater.

noun

1. the water beneath the surface.

   cold currents in the underwater.

2. underwaters, the depths, as of a sea, lake, etc.

underwater British  

/ ˈʌndəˈwɔːtə /

adjective

1. being, occurring, or going under the surface of the water, esp the sea

   underwater exploration

2. nautical below the water line of a vessel

3. (of a stock option or other asset) having a market value below its purchase value

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adverb

1. beneath the surface of the water

Etymology

Origin of underwater

First recorded in 1620–30; under- + water

Example Sentences

We’re sitting on opposite ends of an underwater “sea-saw.”

From Los Angeles Times • Jun. 1, 2026

South Yorkshire Police said his family were "living every parent's worst nightmare", with searches including an underwater team and Mountain Rescue volunteers.

From BBC • Jun. 1, 2026

"They are extremely colorful and can be spotted on coral reef ecosystems. However, many nudibranchs are very small in size and are extremely difficult to spot underwater with the naked eye."

From Science Daily • May 27, 2026

It said "reservoirs can be extremely dangerous, despite appearing calm and safe" adding they can contain "hidden hazards including very cold water, deep and steep-sided banks, strong currents, underwater machinery and sudden drops".

From BBC • May 26, 2026

As Sam Macdonald, the president of the underwater robotics company Deep Trekker, has stated, “The technologies available now, even compared to five or six years ago, are incredible.”

From "Shipwrecked!" by Martin W. Sandler

Related Words

• submerged
• undersea