The Collaborative International Dictionary of English v.0.48:

Macrocosm \Mac"ro*cosm\, n. [Macro- + Gr. ? the world: cf. F.
   macrocosme.]
   The great world; that part of the universe which is exterior
   to man; -- contrasted with microcosm, or man. See
   Microcosm.
   [1913 Webster]

WordNet (r) 3.0 (2006):

macrocosm
    n 1: everything that exists anywhere; "they study the evolution
         of the universe"; "the biggest tree in existence" [syn:
         universe, existence, creation, world, cosmos,
         macrocosm]