1situated, occurring, or done beneath the surface of the water: [as adjective]:there are underwater volcanoes in the region [as adverb]:the seal spent a lot of time underwater
2chiefly US relating to or denoting a loan with a balance that exceeds the current market value of the loan: [as adjective]:an epidemic of underwater mortgages [as adverb]:those who bought new pads in the mid-eighties were underwater for more than a decade
