The Collaborative International Dictionary of English v.0.48:

Assemblage \As*sem"blage\, n. [Cf. F. assemblage. See
   Assemble.]
   1. The act of assembling, or the state of being assembled;
      association.
      [1913 Webster]

            In sweet assemblage every blooming grace. --Fenton.
      [1913 Webster]

   2. A collection of individuals, or of individuals, or of
      particular things; as, a political assemblage; an
      assemblage of ideas.
      [1913 Webster]

   Syn: Company; group; collection; concourse; gathering;
        meeting; convention.

   Usage: Assemblage, Assembly. An assembly consists only of
          persons; an assemblage may be composed of things as
          well as persons, as, an assemblage of incoherent
          objects. Nor is every assemblage of persons an
          assembly; since the latter term denotes a body who
          have met, and are acting, in concert for some common
          end, such as to hear, to deliberate, to unite in
          music, dancing, etc. An assemblage of skaters on a
          lake, or of horse jockeys at a race course, is not an
          assembly, but might be turned into one by collecting
          into a body with a view to discuss and decide as to
          some object of common interest.
          [1913 Webster]

WordNet (r) 3.0 (2006):

assemblage
    n 1: a group of persons together in one place [syn: gathering,
         assemblage]
    2: a system of components assembled together for a particular
       purpose [syn: hookup, assemblage]
    3: the social act of assembling; "they demanded the right of
       assembly" [syn: assembly, assemblage, gathering] [ant:
       disassembly, dismantlement, dismantling]
    4: several things grouped together or considered as a whole
       [syn: collection, aggregation, accumulation,
       assemblage]