The Collaborative International Dictionary of English v.0.48:

Seneschal \Sen"es*chal\, n. [OF. seneschal, LL. seniscalcus, of
   Teutonic origin; cf. Goth. sineigs old, skalks, OHG. scalch,
   AS. scealc. Cf. Senior, Marshal.]
   An officer in the houses of princes and dignitaries, in the
   Middle Ages, who had the superintendence of feasts and
   domestic ceremonies; a steward. Sometimes the seneschal had
   the dispensing of justice, and was given high military
   commands.
   [1913 Webster]

         Then marshaled feast
         Served up in hall with sewers and seneschale. --Milton.
   [1913 Webster]

         Philip Augustus, by a famous ordinance in 1190, first
         established royal courts of justice, held by the
         officers called baitiffs, or seneschals, who acted as
         the king's lieutenants in his demains.   --Hallam.
   [1913 Webster]

WordNet (r) 3.0 (2006):

seneschal
    n 1: the chief steward or butler of a great household [syn:
         major-domo, seneschal]