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

Researchers believe volcanic activity triggered an underwater landslide and caused a large chunk of Anak Krakatau’s southwest slope to collapse and displace a large volume of water. — Tatan Syuflana, Los Angeles Times, 6 Sep. 2026

The government razed or burned its buildings to keep them from becoming underwater hazards in the lake. — Graham Womack, Sacbee.com, 6 Sep. 2026

The first time, parts of the course were literally underwater. — Langston Wertz Jr, Charlotte Observer, 6 Sep. 2026

Some recent polls show the president is even underwater in Texas, where Democrats are hoping to win a Senate race for the first time in decades and plan to stage counterprogramming outside the convention. — Zac Anderson, USA Today, 6 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