WYATT. Has gone through the various forms of Wyat, Wiat, Wyot, and Guyot, or Guiot. The last-named three are used indifferently in the time of King John, and clearly prove the derivation of the name as a diminuti\'e, from the Norman-French personal name Gui or Guido, which we have also received in the form of Guj'. The name Guyatt is still found in West Sussex.

Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.