u-

from The Collaborative International Dictionary of English v.0.48
Molt \Molt\, Moult \Moult\, v. i. [imp. & p. p. {Molted} or
   {Moulted}; p. pr. & vb. n. {Molting} or {Moulting}.] [OE.
   mouten, L. mutare. See {Mew} to molt, and cf. {Mute}, v. t.]
   [The prevalent spelling is, perhaps, {moult}; but as the {u}
   has not been inserted in the otherwords of this class, as,
   bolt, colt, dolt, etc., it is desirable to complete the
   analogy by the spelling {molt}.]
   To shed or cast the hair, feathers, skin, horns, or the like,
   as an animal or a bird. --Bacon.
   [1913 Webster] Molt
    
from The Collaborative International Dictionary of English v.0.48
U \U\ ([=u]),
   the twenty-first letter of the English alphabet, is a cursive
   form of the letter V, with which it was formerly used
   interchangeably, both letters being then used both as vowels
   and consonants. U and V are now, however, differentiated, U
   being used only as a vowel or semivowel, and V only as a
   consonant. The true primary vowel sound of U, in Anglo-Saxon,
   was the sound which it still retains in most of the languages
   of Europe, that of long oo, as in tool, and short oo, as in
   wood, answering to the French ou in tour. Etymologically U is
   most closely related to o, y (vowel), w, and v; as in two,
   duet, dyad, twice; top, tuft; sop, sup; auspice, aviary. See
   {V}, also {O} and {Y}.
   [1913 Webster] See Guide to Pronunciation, [sect][sect]
   130-144.
   [1913 Webster]
    
from Jargon File (4.4.4, 14 Aug 2003)
u-
 pref.

   Written shorthand for {micro-}; techspeak when applied to metric
   units, jargon when used otherwise. Derived from the Greek letter u the
   first letter of "micro" (and which letter looks a lot like the English
   letter "u").
    

[email protected]