See Also:

U(1) (iou)



U, u. [ju:]
The twenty-first letter of the modern English alphabet and the twentieth of the ancient Roman one, a differentiated form of the letter V. Latin manuscripts written in capitals have V only, but other Latin manuscripts also have a modified form of this, resembling u. Both forms occur in Old English manuscripts: capital V represents either V or U, and the modified form usually represents the vowel u. In Middle English the symbols u and v both occur, but without formal distinction of use. During the 16th cent. continental printers began to distinguish lower case u as the vowel symbol and v as the consonant symbol, and by the mid 17th cent. this was also the case in English. Capital V continued to be used for both V and U into the 17th cent., but in the course of that century it was replaced, for the vowel, by capital U. From about 1700 the regular forms have been U u for the vowel, and V v for the consonant. However, many dictionaries etc. continued into the 19th cent. to give items beginning with u or v in a single alphabetic sequence. In Old English the vowel u was sounded either short or long. In Middle English short u remained while long u was replaced in spelling by ou, adopted from French spelling. Also borrowed at this time were the sounds of long and short French u, pronounced with lip-rounding. In mod. English the Old English short u has normally become , over, finished, beyond remedy. slang.
Physics. [German ungerade odd.] (Usu. italic u.) Designating functions, esp. wave functions, which change sign on inversion through the origin, and atomic states etc. represented by such functions. Cf. G, G 8.
Physics. U-process, u-process, = UMKLAPP PROCESS.
III.
Abbrevs.: (A small selection only is given here. Those all in caps. or small caps. also occur with a full stop after each letter; some of those all in caps. also occur (i) with initial cap. only, (ii) in small caps.) U = universal (in a film censorship classification); university; (Chemistry) uranium. u (Particle Physics) = up.