The Collaborative International Dictionary of English v.0.48:

Major-domo \Ma`jor-do"mo\, n. [Sp. mayordomo, or It.
   maggiordomo; both fr. LL. majordomus; L. major greater +
   domus house.]
   A man who has authority to act, within certain limits, as
   master of the house; a steward; also, a chief minister or
   officer.
   [1913 Webster]

WordNet (r) 3.0 (2006):

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

Moby Thesaurus II by Grady Ward, 1.0:

20 Moby Thesaurus words for "majordomo":
   MC, attorney, bailiff, butler, chamberlain, croupier, curator,
   custodian, emcee, factor, guardian, house steward, housekeeper,
   landreeve, librarian, master of ceremonies, proctor, procurator,
   seneschal, steward