In English, the name of the letter is the "long U" sound, pronounced/ˈjuː/. In most other languages, its name matches the letter's pronunciation inopen syllables.
Pronunciation of the name of the letter⟨u⟩ in European languages
U derives from the Semiticwaw, as doesF, and later,Y,W, andV. Its oldest ancestor goes back toEgyptian hieroglyphs, and is probably from a hieroglyph of a mace orfowl, representing the sound[v] or the sound[w]. This was borrowed to Phoenician, where it represented the sound[w], and seldom the vowel[u].
InGreek, two letters were adapted from the Phoenician waw. The letter was adapted, but split in two, withDigamma or wau⟨Ϝ⟩ being adapted to represent[w], and the second one beingUpsilon⟨Υ⟩, which was originally adapted to represent[u], later fronted, becoming[y].
InLatin, a stemless variant shape of the upsilon was borrowed in early times as U, taking the form of modern-dayV – either directly from theWestern Greek alphabet or from theEtruscan alphabet as an intermediary – to represent the same/u/ sound, as well as the consonantal/w/,num – originally spelledNVM – was pronounced/num/ andvia was pronounced[ˈwia]. From the 1st century AD on, depending onVulgar Latin dialect, consonantal/w/ developed into/β/ (kept inSpanish), then later to/v/.
During the lateMiddle Ages, two minuscule forms developed, which were both used for/v/ or the vowel/u/. The pointed form⟨v⟩ was written at the beginning of a word, while a rounded form⟨u⟩ 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⟨v⟩ as distinct letters is in a Gothic alphabet from 1386, where⟨v⟩ preceded⟨u⟩. Printers eschewed capital⟨U⟩ in favor of⟨V⟩ into the 17th century and the distinction between the two letters was not fully accepted by the French Academy until 1762.[4][5][better source needed] The rounded variant became the modern-day version of U and its former pointed form becameV.
InEnglish, the letter⟨u⟩ has four main pronunciations. There are "long" and "short" pronunciations. Short⟨u⟩, found originally in closed syllables, most commonly represents/ʌ/ (as in 'duck'), though it retains its old pronunciation/ʊ/ afterlabial 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⟨ou⟩), most commonly represents/juː/ (as in 'mule'), reducing to/uː/ after⟨r⟩ (as in 'rule'),⟨j⟩ (as in 'June') and sometimes (or optionally) after⟨l⟩ (as in 'lute'), and after additional consonants in American English (ado–dew merger). (After⟨s⟩,/sjuː,zjuː/ have assimilated to/ʃuː,ʒuː/ in some words.)
The letter⟨u⟩ is used in the digraphs⟨au⟩/ɔː/,⟨ou⟩ (various pronunciations, but usually/aʊ/), and with the value of long⟨u⟩ in⟨eu⟩,⟨ue⟩, and in a few words⟨ui⟩ (as in 'fruit'). It often has the sound/w/ before a vowel in the sequences⟨qu⟩ (as in 'quick'),⟨gu⟩ (as in 'anguish'), and⟨su⟩ (as in 'suave'), though it is silent in final⟨que⟩ (as in 'unique') and in many words with⟨gu⟩ (as in 'guard').
Additionally, the letter⟨u⟩ is used intext messaging, theInternet, and other written slang to denote 'you', by virtue of both being pronounced/juː/.
Certain varieties of the English language (i.e.British English,Canadian English, etc.) use the letter U in words such ascolour,labour,valour, etc. InAmerican English, the letter is not used, and the words mentioned are spelled ascolor and so on.
It is the thirteenth most frequently used letter in the English language,[when?] with a frequency of about 2.8% in words.[8]
Other languages
In most languages that use the Latin alphabet,⟨u⟩ represents theclose back rounded vowel/u/ or a similar vowel.[9]
'U' is also the source of the mathematical symbol ∪, representing aunion. It is used mainly forVenn diagrams andgeometry.
It is used formicro- in metric measurements as a replacement for the Greek letterμ (mu), of which it is a graphic approximation when that Greek letter is not available, as in "um" forμm (micrometer).