The Collaborative International Dictionary
Abbot of Unreason
Unreason \Un*rea"son\, n. [Pref. un- not + reason.] Want of reason; unreasonableness; absurdity.
Abbot of Unreason. See Abbot of Misrule, under Abbot.
Wiktionary
abbot of unreason
n. (context usually capitalized English) Elected leader in old Scottish celebrations; Lord of Misrule.(R:MW3 1976)