Definitions
1.nounThe name of the Latin-script letter U.
2.nounA thing in the shape of the letter U
3.pronoun(abbreviation) you (in text messaging and internet conversations)"Take me with u."
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."