Source : Webster's Revised Unabridged Dictionary (1913)

Abbot \Ab"bot\, n. [AS. abbod, abbad, L. abbas, abbatis, Gr.
   'abba^s, fr. Syriac abb[=a] father. Cf. {Abba}, {Abb['e]}.]
   1. The superior or head of an abbey.

   2. One of a class of bishops whose sees were formerly abbeys.
      --Encyc. Brit.

   {Abbot of the people}. a title formerly given to one of the
      chief magistrates in Genoa.

   {Abbot of Misrule} (or {Lord of Misrule}), in medi[ae]val
      times, the master of revels, as at Christmas; in Scotland
      called the {Abbot of Unreason}. --Encyc. Brit.

Source : WordNet®

Lord of Misrule
     n : a person appointed master of revels at a Christmas
         celebration