U

In English, 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/ 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 ⟨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 (see do–dew merger). (After ⟨s⟩, /sjuː, zjuː/ have assimilated to /ʃuː, ʒuː/ in some words) In a few words, short ⟨u⟩ represents other sounds, such as /ɪ/ in 'business' and /ɛ/ in 'bury'.

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 in text messaging, Internet and other written slang to denote 'you', by virtue of both being pronounced /juː/.

One thing to note is that 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.; however, in American English the letter is not used and said 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.

In most languages that use the Latin alphabet, ⟨u⟩ represents the close back rounded vowel /u/ or a similar vowel.[7]

• In French orthography the letter represents the close front rounded vowel /y/; /u/ is represented by ⟨ou⟩.
• In Dutch and Afrikaans, it represents either /y/, or a near-close near-front rounded vowel /ʏ/; likewise, the phoneme /u/ is represented by ⟨oe⟩.
• In Welsh orthography the letter can represent a long close front unrounded vowel /iː/ or short near-close near-front unrounded vowel /ɪ/ in Southern dialects. In Northern dialects, the corresponding long and short vowels are a long close central unrounded vowel /ɨː/ and a short lowered close central unrounded vowel /ɨ̞/, respectively. /uː/ and /ʊ/ are represented by ⟨w⟩.

• ⟨𐤅‎⟩: Semitic letter Waw, from which the following symbols originally derive
  • ⟨Υ υ⟩: Greek letter Upsilon, from which U derives
    • ⟨V v⟩: Latin letter V, descended from U
      • ⟨W w⟩: Latin letter W, descended from V/U
    • ⟨Y y⟩: Latin letter Y, also descended from Upsilon
    • ⟨У у⟩: Cyrillic letter U, which also derives from Upsilon
    • ⟨Ү ү⟩: Cyrillic letter Ue
  • ⟨Ϝ ϝ⟩: Greek letter Digamma
    • ⟨F f⟩: Latin letter F, derived from Digamma
• IPA-specific symbols related to U: ⟨ʊ⟩ ⟨ɥ⟩
• Uralic Phonetic Alphabet-specific symbols related to U:[9]
  • U+1D1C ᴜ LATIN LETTER SMALL CAPITAL U
  • U+1D41 ᵁ MODIFIER LETTER CAPITAL U
  • U+1D58 ᵘ MODIFIER LETTER SMALL U
  • U+1D64 ᵤ LATIN SUBSCRIPT SMALL LETTER U
  • U+1D1D ᴝ LATIN SMALL LETTER SIDEWAYS U
  • U+1D1E ᴞ LATIN SMALL LETTER SIDEWAYS DIAERESIZED U
  • U+1D59 ᵙ MODIFIER LETTER SMALL SIDEWAYS U
• Teuthonista phonetic transcription-specific symbols related to U:[10]
  • U+AB4E ꭎ LATIN SMALL LETTER U WITH SHORT RIGHT LEG
  • U+AB4F ꭏ LATIN SMALL LETTER U BAR WITH SHORT RIGHT LEG
  • U+AB51 ꭑ LATIN SMALL LETTER TURNED UI
  • U+AB52 ꭒ LATIN SMALL LETTER U WITH LEFT HOOK
  • U+AB5F ꭟ MODIFIER LETTER SMALL U WITH LEFT HOOK
• U+1DB8 ᶸ MODIFIER LETTER SMALL CAPITAL U: used for phonetic transcription[11]
• ⟨Ꞿ ꞿ⟩: Glottal U, used in the transliteration of Ugaritic[12]
• U with diacritics: ⟨Ŭ ŭ Ʉ ʉ ᵾ⟩[11] ⟨ᶶ⟩[11] ⟨Ꞹ⟩[13] ⟨ꞹ⟩[13] ⟨Ụ ụ⟩ ⟨Ü ü⟩ ⟨Ǜ ǜ⟩ ⟨Ǘ ǘ⟩ ⟨Ǚ ǚ⟩ ⟨Ǖ ǖ⟩ ⟨Ṳ ṳ⟩ ⟨Ú ú⟩ ⟨Ù ù⟩ ⟨Û û Ṷ ṷ⟩ ⟨Ǔ ǔ⟩ ⟨Ȗ ȗ⟩ ⟨Ű ű⟩ ⟨Ŭ ŭ⟩ ⟨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⟩[11] ⟨Ų ų Ų́ ų́ Ų̃ ų̃⟩ ⟨Ȕ ȕ⟩ ⟨Ů ů⟩
  • U+A7B8 Ꞹ LATIN CAPITAL LETTER U WITH STROKE and U+A7B9 ꞹ LATIN SMALL LETTER U WITH STROKE are used in the Mazahua language and feature a bar diacritic

• ∪: Union
• ∩: Intersection, an upside-down upper case "U"