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

But amazing advances in underwater discovery and excavation technology have made the finding and recovery of even the most seemingly inaccessible wrecks more possible than previously thought.

From "Shipwrecked!" by Martin W. Sandler

Related Words

• submerged
• undersea