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

Underwater mortgages were also less common in the Midwest, the Northeast and the West Coast.

From MarketWatch • Feb. 9, 2026

Underwater sound can travel far, particularly at low frequencies.

From Science Daily • Feb. 5, 2026

Eventually Mr. Dooley and his older brother would found Cuba’s Department of Underwater Investigations “with a mission,” Mr. Sancton writes, “to explore Cuba’s largely uncharted continental shelf.”

From The Wall Street Journal • Jan. 21, 2026

Underwater and forsaken, American homeowners watched as their earth-toned Tuscan kitchens and quirky bits of ornament made their homes slow to move in a glutted market.

From Salon • Aug. 23, 2025

Underwater ferns weave in spirals toward the shore from the deeper water.

From "The Last Cuentista" by Donna Barba Higuera

Related Words

• submerged
• undersea