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
see also:
molted moulted molting moulting mew mute 
moult u molt