Definitions
1.nounUnderlying water or body of water, for example in an aquifer or the deep ocean
2.nounA type of lure which lies beneath the water surface.
3.verbTo water or irrigate insufficiently"Care must be taken not to underwater houseplants in the summer."
4.adjectiveBeneath the surface of the water, or of or pertaining to the region beneath the water surface
5.adjectiveBeneath the water line of a vessel
6.adjectiveUnder water.
7.adjectiveHaving negative equity; owing more on an asset than its market value"We've been underwater on our mortgage ever since the housing crash."
8.adverbGoing beneath the surface of the water