U

U, or u, is the twenty-first letter and the fifth vowel letter of the Latin alphabet, used in the modern English alphabet and the alphabets of other western European languages and others worldwide. Its name in English is u (pronounced ), plural ues.

Name
In English, the name of the letter is the "long U" sound, pronounced. In most other languages, its name matches the letter's pronunciation in open syllables.

History
U derives from the Semitic waw, as does F, and later, Y, W, and V. Its oldest ancestor goes back to Egyptian hieroglyphs, and is probably from a hieroglyph of a mace or fowl, representing the sound or the sound. This was borrowed to Phoenician, where it represented the sound, and seldom the vowel.

In Greek, two letters were adapted from the Phoenician waw. The letter was adapted, but split in two, with Digamma or wau $⟨u⟩$ being adapted to represent, and the second one being Upsilon $⟨⟩$, which was originally adapted to represent , later fronted, becoming.

In Latin, a stemless variant shape of the upsilon was borrowed in early times as U, taking the form of modern-day V – either directly from the Western Greek alphabet or from the Etruscan alphabet as an intermediary – to represent the same sound, as well as the consonantal, num – originally spelled  NVM  – was pronounced  and via was pronounced. From the 1st century AD on, depending on Vulgar Latin dialect, consonantal developed into  (kept in Spanish), then later to.

During the late Middle Ages, two minuscule forms developed, which were both used for or the vowel. The pointed form $⟨⟩$ was written at the beginning of a word, while a rounded form $⟨v⟩$ was used in the middle or end, regardless of sound. So whereas 'valour' and 'excuse' appeared as in modern printing, 'have' and 'upon' were printed 'haue' and 'vpon', respectively. The first recorded use of $⟨u⟩$ and $⟨u⟩$ as distinct letters is in a Gothic alphabet from 1386, where $⟨v⟩$ preceded $⟨v⟩$. Printers eschewed capital $⟨u⟩$ in favor of $⟨U⟩$ into the 17th century and the distinction between the two letters was not fully accepted by the French Academy until 1762. The rounded variant became the modern-day version of U and its former pointed form became V.

English
In English, the letter has four main pronunciations. There are "long" and "short" pronunciations. Short $⟨V⟩$, found originally in closed syllables, most commonly represents (as in 'duck'), though it retains its old pronunciation  after labial consonants in some words (as in 'put') and occasionally elsewhere (as in 'sugar'). Long $⟨u⟩$, found originally in words of French origin (the descendant of Old English long $⟨u⟩$ was respelled as $⟨u⟩$), most commonly represents (as in 'mule'), reducing to  after $⟨u⟩$ (as in 'rule'), $⟨ou⟩$ (as in 'June') and sometimes (or optionally) after $⟨r⟩$ (as in 'lute'), and after additional consonants in American English (a do–dew merger). (After $⟨j⟩$, have assimilated to  in some words.)

The letter $⟨l⟩$ is used in the digraphs $⟨s⟩$, $⟨u⟩$ (various pronunciations, but usually ), and with the value of long $⟨au⟩$ in $⟨ou⟩$, $⟨u⟩$, and in a few words $⟨eu⟩$ (as in 'fruit'). It often has the sound before a vowel in the sequences $⟨ue⟩$ (as in 'quick'), $⟨ui⟩$ (as in 'anguish'), and $⟨qu⟩$ (as in 'suave'), though it is silent in final $⟨gu⟩$ (as in 'unique') and in many words with $⟨su⟩$ (as in 'guard').

Additionally, the letter $⟨que⟩$ is used in text messaging, the Internet, and other written slang to denote 'you', by virtue of both being pronounced.

Certain varieties of the English language (i.e. British English, Canadian English, etc.) use the letter U in words such as colour, labour, valour, etc. In American English, the letter is not used, and the words mentioned are spelled as color and so on.

It is the thirteenth most frequently used letter in the English language, with a frequency of about 2.8% in words.

Other languages
In most languages that use the Latin alphabet, $⟨gu⟩$ represents the close back rounded vowel or a similar vowel.


 * In French orthography the letter represents the close front rounded vowel ; is represented by $⟨u⟩$.
 * In Dutch and Afrikaans, it represents either, or a near-close near-front rounded vowel ; likewise, the phoneme is represented by $⟨u⟩$.
 * In Welsh orthography the letter can represent a long close front unrounded vowel or short near-close near-front unrounded vowel  in Southern dialects. In Northern dialects, the corresponding long and short vowels are a long close central unrounded vowel  and a short lowered close central unrounded vowel, respectively.  and  are represented by $⟨ou⟩$.

Other systems
The International Phonetic Alphabet uses ⟨u⟩ for the close back rounded vowel.

Other uses

 * The symbol 'U' is the chemical symbol for uranium.
 * In the context of Newtonian mechanics, 'U' is the symbol for the potential energy of a system.
 * 'u' is the symbol for the atomic mass unit, and 'U' is the symbol for one enzyme unit.
 * In the International Phonetic Alphabet, the close back rounded vowel is represented by the lowercase $⟨oe⟩$.
 * U is also the source of the mathematical symbol ∪, representing a union. It is used mainly for Venn diagrams and geometry.
 * It is used for micro- in metric measurements as a replacement for the Greek letter μ (mu), of which it is a graphic approximation when that Greek letter is not available, as in " " for μm (micrometer).
 * Some universities, such as the University of Miami and the University of Utah, are locally known as "The U".
 * U (or sometimes RU) is a standard height unit of measure in rack units, with each U equal to 44.50 mm.
 * U is used as the symbol of the World War II organization Ustaše.
 * U is an honorific in Burmese.

Ancestors, descendants and siblings

 * $⟨w⟩$: Semitic letter Waw, from which the following symbols originally derive:
 * $⟨u⟩$: Greek letter Upsilon, from which U derives
 * $⟨⟩$: Latin letter V, descended from U
 * $⟨⟩$: Latin letter W, descended from V/U
 * $⟨V v⟩$: Latin letter Y, also descended from Upsilon
 * $⟨W w⟩$: Cyrillic letter U, which also derives from Upsilon
 * $⟨Y y⟩$: Cyrillic letter Ue
 * $⟨⟩$: Greek letter Digamma
 * $⟨⟩$: Latin letter F, derived from Digamma
 * IPA-specific symbols related to U:
 * Uralic Phonetic Alphabet-specific symbols related to U:
 * Teuthonista phonetic transcription-specific symbols related to U:
 * : used for phonetic transcription
 * $⟨⟩$: Glottal U, used in the transliteration of Ugaritic
 * U with diacritics: $⟨F f⟩$ $⟨Ꞿ ꞿ⟩$ $⟨Ŭ|Ŭ ŭ Ʉ|Ʉ ʉ ᵾ⟩$ $⟨ᶶ⟩$ $⟨Ꞹ⟩$ $⟨ꞹ⟩$ $⟨Ụ ụ⟩$ $⟨Ü|Ü ü⟩$ $⟨Ǜ ǜ⟩$ $⟨Ǘ ǘ⟩$ $⟨Ǚ ǚ⟩$ $⟨Ǖ ǖ⟩$ $⟨Ṳ ṳ⟩$ $⟨Ú|Ú ú⟩$ $⟨Ù|Ù ù⟩$ $⟨Û û Ṷ ṷ⟩$ $⟨Ǔ ǔ⟩$ $⟨Ȗ|Ȗ ȗ⟩$ $⟨Ű ű⟩$ $⟨Ŭ|Ŭ ŭ⟩$ $⟨Ư|Ư ư⟩$ $⟨Ứ ứ⟩$ $⟨Ừ ừ⟩$ $⟨Ử ử⟩$ $⟨Ự ự⟩$ $⟨Ữ Ữ⟩$ $⟨Ủ ủ⟩$ $⟨Ū ū⟩$ $⟨Ū̀ ū̀⟩$ $⟨Ū́ ū́⟩$ $⟨Ṻ ṻ⟩$ $⟨Ū̃ ū̃⟩$ $⟨Ũ ũ⟩$ $⟨Ṹ ṹ⟩$ $⟨Ṵ ṵ⟩$ $⟨ᶙ⟩$ $⟨Ų ų Ų́ ų́ Ų̃ ų̃⟩$
 * and are used in the Mazahua language and feature a bar diacritic.
 * Teuthonista phonetic transcription-specific symbols related to U:
 * : used for phonetic transcription
 * $⟨Ȕ ȕ⟩$: Glottal U, used in the transliteration of Ugaritic
 * U with diacritics: $⟨Ů ů⟩$ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭
 * and are used in the Mazahua language and feature a bar diacritic.
 * : used for phonetic transcription
 * ⇭⇭⇭: Glottal U, used in the transliteration of Ugaritic
 * U with diacritics: ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭
 * and are used in the Mazahua language and feature a bar diacritic.
 * ⇭⇭⇭: Glottal U, used in the transliteration of Ugaritic
 * U with diacritics: ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭ ⇭⇭⇭
 * and are used in the Mazahua language and feature a bar diacritic.

Ligatures and abbreviations

 * ∪: Union, an infix notation.
 * ∩: Intersection, an infix notation.