 The word "falcon" existed simultaneously as homonyms "fauco(u)n" and "falcon" in Middle English.The word "moult/molt" never originally had to begin with, instead deriving from Middle English "mout" and related etymologically to "mutate"; the joined the word intrusively.The Great Vowel Shift changed the diphthongs to their present pronunciations, with becoming the monophthong , and raising to .