undersea

1 of 2

adjective

un·​der·​sea ˌən-dər-ˈsē How to pronounce undersea (audio)
Synonyms of underseanext
1
: being or carried on under the sea or under the surface of the sea
undersea oil deposits
undersea fighting
2
: designed for use under the surface of the sea
an undersea fleet

undersea

2 of 2

adverb

variants or underseas
ˌən-dər-ˈsēz How to pronounce undersea (audio)
: under the sea : beneath the surface of the sea
photographs taken undersea

Examples of undersea in a Sentence

Adjective They are conducting undersea research.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Adjective
The Baltic initiative comes amid broader efforts by NATO and regional governments to protect an area increasingly associated with threats to undersea cables, pipelines, shipping and other critical infrastructure. — Efrat Lachter, FOXNews.com, 5 Sep. 2026 An undersea cable for an electricity project was set to go right through the popular mound of stones, but protesters were not having it. — Maureen O'Hare, CNN Money, 5 Sep. 2026 All the 2026 finalists of Ocean Photographer Of The Year demonstrate the power of undersea photography to reveal unseen ecosystems, document environmental challenges and inspire greater care for the ocean. — Cecilia Rodriguez, Forbes.com, 23 Aug. 2026 As governments, research institutions, and privateers struggle to afford undersea excursions, a new class of patron has joined the pursuit. — Brett Berk, Robb Report, 22 Aug. 2026 See All Example Sentences for undersea

Word History

First Known Use

Adjective

1613, in the meaning defined at sense 1

Adverb

1645, in the meaning defined above

Time Traveler
The first known use of undersea was in 1613

Rhymes for undersea

See All Rhymes for undersea

Browse Nearby Words

under scrutiny
undersea
under seal
See all Nearby Words

Cite this Entry

“Undersea.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/undersea. Accessed 7 Sep. 2026.

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Kids Definition

undersea

adjective
un·​der·​sea
ˈən-dər-ˈsē
1
: being or carried on under the sea or under the surface of the sea
undersea oil deposits
undersea warfare
2
: designed for use under the surface of the sea
undersea fleet

More from Merriam-Webster on undersea

Thesaurus: All synonyms and antonyms for undersea

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