its old pronunciation after labial consonants in some words (as in 'put') and occasionally elsewhere (as in 'sugar'). Long , found originally in words of French origin (the descendant of Old English long u was respelled as ), most commonly represents (as in 'mule'), reducing to after (as in 'rule'), (as in 'June') and sometimes (or optionally) after (as in 'lute'), and after additional consonants in American English (see do–dew merger). (After , have assimilated to in some words) In a few words, short represents other sounds, such as in 'business' and in 'bury'. The letter is used in the digraphs , (various pronunciations, but usually /aʊ/), and with the value of "long u" in , , and in a few words (as in 'fruit'). It often has the sound before a vowel in the sequences (as in 'quick'), (as in 'anguish'), and (as in 'suave'), though it is silent in final -que (as in 'unique') and in many words with (as in 'guard'). Additionally, the letter is used in text messaging, Internet and other written slang to denote 'you', by virtue of both being pronounced . 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. Other languages In most languages that use the Latin alphabet, represents the close back rounded vowel or a similar vowel. In French orthography the letter represents the close front rounded vowel (); is represented by . In Dutch and Afrikaans, it represents either , or a near-close near-front rounded vowel (); likewise, the phoneme is represented by . 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 . 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'