U

U (u) is the twenty-first (number 21) letter in the English alphabet. It is pronounced "yoo".

Meanings for U

On calendars, U is most times a short letter for Sunday, for use when S is being used for Saturday.
In chemistry, U is the symbol for uranium.
Sometimes used as a short form of "you".
It is the seventh letter on the QWERTY keyboard.

The dictionary definition of u at Wiktionary
Media related to U at Wikimedia Commons