\Arch"es\,
pl. of {Arch}, n.
{Court of arches}, or {Arches Court} (Eng. Law), the court of
   appeal of the Archbishop of Canterbury, whereof the judge,
   who sits as deputy to the archbishop, is called the Dean
   of the Arches, because he anciently held his court in the
   church of St. Mary-le-Bow (de arcubus). It is now held in
   Westminster. --Mozley & W.