un ‧ der ‧ wa ‧ ter /ˌʌndəˈwɔːtə◂ $ ˌʌndərˈwɒːtər◂, -ˈwɑː-/ BrE AmE adjective [only before noun]
[ Word Family: adjective : ↑ underwater , water, ↑ waterless ; noun : ↑ water , waters; verb : ↑ water ; adverb : ↑ underwater ]
below the surface of an area of water, or able to be used there:
an underwater camera
—underwater adverb :
He dived underwater and swam away.