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

Thales said it was benefiting from sustained demand as events in the Middle East had made its defense products more relevant, particularly in air defense, air surveillance and underwater mine warfare.

From The Wall Street Journal • Apr. 21, 2026

As plants break down underwater, they form methane, which then bubbles to the surface.

From Los Angeles Times • Apr. 15, 2026

In the leadup to that downturn, investors did not know which banks held the losses from pools of underwater subprime mortgages when the housing market collapsed.

From MarketWatch • Apr. 14, 2026

The Russian embassy has previously said it was "not interested in British underwater communications."

From BBC • Apr. 9, 2026

Chica would be safer on the sandy sea bottom off Turtle Beach, but sea lions can’t stay underwater forever.

From "Nim’s Island" by Wendy Orr

Related Words

• submerged
• undersea