The Collaborative International Dictionary of English v.0.48:

Secretariat \Sec`re*ta"ri*at\, Secretariate \Sec`re*ta"ri*ate\,
   n. [F. secr['e]tariat.]
   The office of a secretary; the place where a secretary
   transacts business, keeps records, etc.
   [1913 Webster]

WordNet (r) 3.0 (2006):

secretariate
    n 1: an administrative unit responsible for maintaining records
         and other secretarial duties; especially for international
         organizations [syn: secretariat, secretariate]