Article: U

U is also the atomic symbol for Uranium.

The letter U is the twenty-first letter in the Latin alphabet. Its English name is pronounced [ju:].

U, developed in the late Middle Ages, was originally a positional variant of the letter V, as J was of I, used only in lower-case writing and only medially, and representing both the vowels now written with U and the consonants now written with V. The use of the two forms to distinguish the consonants and vowels which they now represent was not standardised until the 18th century.

Codes for computing

Alternative representations for U
NATO phonetic Morse code
Uniform ··–
10934-75px-ics-uniform-svg-u.png 10935-90px-semaphore-uniform-svg-u.png 10936-asl-uniform-u.png 10937-77px-braille-u-svg-u.png
Signal flag Semaphore ASL Manual Braille

In Unicode the capital U is codepoint U+0055 and the lowercase u is U+0075.

The ASCII code for capital U is 85 and for lowercase u is 117; or in binary 01010101 and 01110101, correspondingly.

The EBCDIC code for capital U is 228 and for lowercase u is 164.

The numeric character references in HTML and XML are "U" and "u" for upper and lower case respectively.

Meanings for U

  • In astronomy,
    • U magnitude is an object's magnitude seen through a U (ultraviolet) filter
    • U stands for the planet Uranus; for example, S/2001 U 2 was the second satellite of Uranus sighted in 2001, Ferdinand.
    • U stands for an October 16 through 31 discovery, in the provisional designation of a comet (e.g. P/2005 U1, Comet Read 3) or asteroid (e.g. (4425) 1967 UQ).
  • In biochemistry, U is the symbol for uracil. It is also the symbol for enzyme unit, a standard measure of amount of a particular enzyme.
  • In Burmese, U is an honorific roughly equal to Mister.
  • 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 commerce, a circled U, â“Š, on a food product indicates kosher certification by the Orthodox Union.
  • In communication, u is an abbreviation for the word "you" in SMS or instant messages.
  • In computing:
    • 1 U (= 44 mm or 1.75 inch) is a standard unit of height of a piece of equipment or computer chassis in a 19-inch rack, also called a rack unit (RU) or a pizza box.
    • In the C and C++ programming languages, an integer literal may be suffixed with an uppercase U to indicate that it should be interpreted as an unsigned quantity.
  • In education, U is an unsatisfactory grade.
  • In electrical engineering, U is one of the recommended symbols for electric or magnetic potential difference (voltage).
  • In geosciences, U stands for the theoretical geopotential, and U-shaped for glaciated valleys
  • In history, U is king of Goryeo (Korea).
  • In Internet slang, "u" or "U" is referred to as "you" due to the similarity in pronunciation.
  • In Japanese, U is a romanization of the kana う and ウ.
  • 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, 10938-432c1df69e11aba7c5c5070e7578609f-u.png stands for union and the upside-down 10939-e78f632038354aae583f795a73d4e6b8-u.png 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 metrology, u is the symbol for unified atomic mass unit.
  • 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 metrology, u is the symbol for the unified atomic mass unit.
  • In physics,
    • u is one of the recommended symbols for velocity.
    • u is the recommended symbol for the ion displacement vector (solid state physics).
    • u is the recommended symbol for the first lattice direction (solid state physics).
  • U also stands for the popular Shia name Umar, as the latter is considered too sacred to be said aloud.
  • In the SI system (the metric system),
    • u is a nonstandard way of writing the SI prefix mu (μ), denoting 10-6 = 0.000001 (one millionth), and pronounced as micro. This is commonly done in computer programs or computer systems without Unicode font support, where the lowercase u glyph is the closest ASCII approximation to the μ glyph.
  • In sports, U is a common nickname for Universitario de Deportes, one of the most popular soccer teams in Peru.
  • In television engineering, particularly in the PAL encoding system, U is one of the two subcarrier-modulated color-difference channels in the YUV colorspace.
  • In thermodynamics, U is the recommended symbol for a system's internal energy.
  • In the Unicode standard, character code points are labelled "U+" followed by a number in hexadecimal.
  • The U, nickname for several Universities.

See also

Wikimedia Commons has media related to:
  • Ù
  • Ú
  • Û
  • Ãœ
  • Ũ
  • Ŭ
  • Ç“
  • Å°
  • Å®
  • Ū
  • Ų
  • Ư
  • Ụ
  • Ủ
Two-letter combinations
Ua Ub Uc Ud Ue Uf Ug Uh Ui Uj Uk Ul Um Un Uo Up Uq Ur Us Ut Uu Uv Uw Ux Uy Uz
Letter-digit & Digit-letter combinations
U0 U1 U2 U3 U4 U5 U6 U7 U8 U9
0U 1U 2U 3U 4U 5U 6U 7U 8U 9U
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