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

China’s new underwater drone toys The drones are likely intended to be armed with conventional submarine armaments like mines and torpedoes, but could also act as motherships for other drones, too. —Christopher McFadden, Interesting Engineering, 14 Dec. 2025

Three pollsters told Washington Secrets this week that the president is underwater with independent voters, who mostly cite the economy, war and taxes as their issues of concern. —Paul Bedard, The Washington Examiner, 13 Dec. 2025

Over 100 feet longer than Titanic, the vessel’s next life will serve as a thriving habitat for marine life and a new frontier for underwater exploration. —Kelsey Glennon, Southern Living, 12 Dec. 2025

Use an underwater light to set the mood. —Cody Godwin, USA Today, 12 Dec. 2025

Word History

First Known Use

1627, in the meaning defined at sense 1

Rhymes for underwater

• annunciator
• imprimatur
• backwater
• bathwater
• blackwater
• breakwater
• deepwater
• edgewater
• feedwater
• floodwater
• freshwater
• granddaughter

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