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
European consumers can expect natural gas from an undersea deposit off Cyprus to help meet their energy needs as early as March 2028, the island nation’s energy minister said. — Menelaos Hadjicostis, Fortune, 9 Aug. 2026 The latest awards reinforce how those engineering capabilities are being applied to torpedo reliability, submarine maintenance and the long-term readiness of America’s undersea fleet. — Atharva Gosavi, Interesting Engineering, 9 Aug. 2026 In 2022, Anduril expanded into undersea systems with the acquisition of Dive Technologies, whose autonomous underwater vehicles became the basis for its Dive-LD platform. — Encyclopedia Britannica, 7 Aug. 2026 The messaging could lay the groundwork for possible future military demonstrations, including missile tests or displays of undersea strike capabilities, said Lim Eul-chul, a professor at Kyungnam University’s Institute for Far Eastern Studies. — Reuters, NBC news, 5 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 10 Aug. 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

Nglish: Translation of undersea for Spanish Speakers

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