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
That action comes as part of a broader regional war in the Middle East that began when the United States and Israel attacked Iran in February 2026—and Iran has drawn up plans to potentially attack undersea cables if hostilities ramp up once again. — Jeremy Hsu, ArsTechnica, 28 Oct. 2026 Last year, attacks on undersea cables in Eastern Europe’s Baltic Sea, allegedly linked to Russia, disrupted connectivity in Sweden and Latvia, prompting calls from telecom firms for governments to step in. — Will McCurdy, PC Magazine, 24 Oct. 2026 Bits are born in mines, factories, data centers, undersea cables, power grids, and human hands. — Amelia Rose Barlow, Rolling Stone, 22 Oct. 2026 Iranian officials have vowed to widen their attacks to target data centers and undersea internet cables, while refusing concessions on their nuclear program. — Anniek Bao, CNBC, 22 Oct. 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 1 Nov. 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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