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]

Moby Thesaurus II by Grady Ward, 1.0:

32 Moby Thesaurus words for "macrocosm":
   Copernican universe, Einsteinian universe, Newtonian universe,
   Ptolemaic universe, all, all being, all creation, allness, cosmos,
   created nature, created universe, creation, everything that is,
   expanding universe, macrocosmos, megacosm, metagalaxy, nature,
   omneity, plenum, pulsating universe, sidereal universe,
   steady-state universe, sum of things, system, totality,
   totality of being, universe, whole wide world, wide world, world,
   world without end