U is the twenty-first letter of the modern Latin alphabet.
U was originally a capital letter like J and it was only Pierre de la Ramée who made the distinction between capital and small letter. See V.
Uniform represents the letter U in the NATO phonetic alphabet.
Meanings for U
- University of Utah or "U of U" (or just University in general).
- In a 19-inch rack a rack unit, RU, unit or U is a standard height of 1.75 inches (44.45 mm).
- In biochemistry, U is the symbol for uracil.
- In calendars, U is often an abbreviation for Sunday, for use when S is being used for Saturday.
- In chemistry, U is the symbol for uranium.
- In communication, u is an abbreviation for the word "you" in SMS or instant message.
- In computing, 1 U (= 44 mm or 1.75 inch) is a standard unit of height of computer chassis, also called a rack unit or a pizza box.
- In education, U is an unsatisfactory grade.
- In electrical engineering, U is the symbol for voltage.
- In linguistics, U refers to speech markers of upper class British speakers. British novelist Nancy Mitford brought to popular attention the linguistic terminology "U" and "non-U" to indicate the speech markers of upper class and non-upper class British speakers respectively.
- In mathematics,
stands for union and the upside-down 
stands for intersection (both are operators on sets). A U-set is a set of uniqueness.
- In mathematics, U stands for the unitary group.
- In military science, U- is a prefix used for German submarines during World War II, (e.g., U-20), which was short for Unterseeboot. They were also referred to as "U-boats" by the Allies.
- In the Unicode standard, character code points are labelled "U+" followed by a number in hexadecimal.
See also
