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

The helmets survived in exceptional condition thanks to a combination of sediment and mineral deposits that formed around them underwater.

From Science Daily • Jun. 8, 2026

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

From Los Angeles Times • Jun. 1, 2026

The US, UK and Australia say they will develop underwater drone technology to protect undersea cables and boost defence, under their military alliance known as Aukus.

From BBC • May 30, 2026

U.S. forces used underwater robots to clear it of mines in the weeks leading up to the operation.

From The Wall Street Journal • May 30, 2026

Then Osei’s voice again, sounding like it’s underwater now.

From "Kwame Crashes the Underworld" by Craig Kofi Farmer

Related Words

• submerged
• undersea