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

Snap some cool underwater photos with the Nite Ize RunOff Waterproof Tablet Case, now 42 percent off. —Sophie Dodd, Travel + Leisure, 16 Jan. 2026

The Reefline Various underwater locations Miami Beach Equal parts artificial reef and underwater sculpture park, The Reefline proves Miami art doesn’t stop at the shoreline. —Outside, 15 Jan. 2026

These vortices push and pull the cylinder, forcing it to swing back and forth like an underwater pendulum. —Mrigakshi Dixit, Interesting Engineering, 15 Jan. 2026

In addition to losing her brother T’Challa in the last movie, Shuri’s mother Queen Ramonda (Angela Bassett) also died when Wakanda was attacked by Namor (Tenoch Huerta) and his underwater kingdom Talokan. —Jordan Moreau, Variety, 13 Jan. 2026

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