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 reason we’re underwater is because most of us is hidden.

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

Researchers explained that strong seasonal weather patterns greatly limit opportunities for underwater surveys.

From Science Daily • May 27, 2026

That pledge unnerved rent-stabilized landlords who own buildings with piles of expensive debt that have been pushed further underwater by the rising cost of insurance, utilities and other expenses.

From The Wall Street Journal • May 26, 2026

Polar bears were great swimmers, but they couldn’t breathe underwater.

From "Two Degrees" by Alan Gratz

Related Words

• submerged
• undersea