undersea

1 of 2

adjective

un·​der·​sea ˌən-dər-ˈsē 

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 

: 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

Adjective

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

The partnership is intended to combine Vatn’s undersea autonomy technology with Taiwan’s research and industrial capabilities, according to NCSIST. — Kaif Shaikh, Interesting Engineering, 19 Aug. 2026

Directed by Kim Soo-hoon, the musical fantasy adventure follows Princess Romi, Heartsping, and their companions exploring an undersea kingdom to rescue Queen Velita. — Naman Ramachandran, Variety, 17 Aug. 2026

Word History

First Known Use

Adjective

1613, in the meaning defined at sense 1

Adverb

1645, in the meaning defined above

Rhymes for undersea

• abc
• absentee
• addressee
• adoptee
• allottee
• amphorae
• amputee
• apc
• apogee
• appointee
• assessee
• assignee

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