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Synonyms

undersea

American  
[uhn-der-see] / ˈʌn dərˌsi /

adjective

  1. located, carried on, or used under the surface of the sea.

    undersea life.


adverb

  1. underseas.

undersea British  
/ ˈʌndəˌsiː /

adjective

  1. below the surface of the sea

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of undersea

First recorded in 1605–15; under- + sea

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

A significant share of global web traffic passes through the Strait via undersea cables, largely servicing countries in the Gulf and South Asia.

From Barron's • Apr. 12, 2026

Britain’s military exposed a month-long, secret Russian submarine operation targeting U.K. undersea infrastructure.

From The Wall Street Journal • Apr. 9, 2026

"Sea mines and other explosive devices can cause acoustic disturbance impacting sea mammals and other animals, and blast damage to natural undersea structures such as reefs," Weir said.

From Barron's • Mar. 17, 2026

As part of her training, she spent 18 days as an aquanaut living in an undersea habitat.

From BBC • Mar. 15, 2026

He was a true renaissance man—a best-selling author, an undersea adventurer, and a discoverer of long-lost ships.

From "Shipwrecked!" by Martin W. Sandler

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