The Collaborative International Dictionary of English v.0.48:

Decentralize \De*cen"tral*ize\, v. t.
   to make less central; to prevent from centralizing; to cause
   to withdraw from the center or place of concentration; to
   divide and distribute (what has been united or concentrated);
   -- esp. said of authority, or the administration of public
   affairs.
   [1913 Webster]

WordNet (r) 3.0 (2006):

decentralize
    v 1: make less central; "After the revolution, food distribution
         was decentralized" [syn: decentralize, deconcentrate,
         decentralise] [ant: centralise, centralize,
         concentrate]