moult: [14] The etymological meaning of moult is simply ‘change’. It comes (via an assumed but never recorded Old English *mūtian) from a prehistoric Germanic verb borrowed from Latin mūtāre ‘change’ (source of English mutate). The extreme semantic narrowing down from ‘change’ to ‘change a coat of feathers’ is shown too in the related mews, which originally denoted ‘cages for moulting hawks’. The spelling with l, which started to appear in the 16th century, is due to association with words such as fault, whose l at that time was generally not pronounced. When it began to be, moult followed suit. => mews, mutate
