underwater

adjective

un·​der·​wa·​ter ˌən-dər-ˈwȯ-tər 

-ˈwä-

1

: lying, growing, worn, performed, or operating below the surface of the water

underwater plants

2

: being below the waterline of a ship

3

a

: having, relating to, or being a mortgage loan for which more is owed than the property securing the loan is worth

homeowners who are underwater on their loans

b

: having, relating to, or being a stock option for which the price of the option is higher than the current market value of the stock

underwater adverb

Synonyms of underwater

• aquatic
• submarine
• submerged

Examples of underwater in a Sentence

underwater plants don't require as much light to grow as surface plants

a vessel designed for underwater exploration

Recent Examples on the Web

Highways, riverside communities and low-lying neighborhoods remain underwater, cutting off dozens of households, killing a Hanoi university student and three villagers, and forcing evacuations of at least 150 families. — Aniruddha Ghosal, Los Angeles Times, 18 Sep. 2026

China appears to be building a large surface vessel specifically designed to launch, recover, and support submarine-sized uncrewed underwater vehicles, according to satellite imagery analyzed by naval experts. — Kaif Shaikh, Interesting Engineering, 17 Sep. 2026

Yorkville Police Department In Yorkville, Illinois, the high school student parking lot was underwater after heavy rainfall. — Shane Hinton, CBS News, 17 Sep. 2026

As is the case with other underwater drones/small ROVs, the BentiX is connected to a communications cable that runs from it to a topside joystick remote control unit (wireless radio signals do not travel well through water). — New Atlas, 16 Sep. 2026

Word History

First Known Use

1627, in the meaning defined at sense 1

Rhymes for underwater

• imprimatur
• auteur
• blotter
• cotter
• daughter
• hotter
• mater
• otter
• plotter
• rotter
• slaughter
• spotter

Kids Definition

underwater

adjective

un·​der·​wa·​ter ˈən-dər-ˈwȯt-ər 

-ˈwät-

: lying, growing, worn, performed, or operating below the surface of the water

underwater plants

an underwater cave

underwater

-ˈwȯt-, 

-ˈwät-

adverb

Legal Definition

underwater

adjective

un·​der·​wa·​ter

1

: owing more on a mortgage loan than the property securing the loan is worth

underwater homeowners

2

: being or relating to a mortgage loan in which more is owed than the property securing the loan is worth

underwater mortgages

underwater properties