The Collaborative International Dictionary of English v.0.48:

Amalgamation \A*mal`ga*ma"tion\, n. [Cf. F. amalgamation.]
   1. The act or operation of compounding mercury with another
      metal; -- applied particularly to the process of
      separating gold and silver from their ores by mixing them
      with mercury. --Ure.
      [1913 Webster]

   2. The mixing or blending of different elements, races,
      societies, etc.; also, the result of such combination or
      blending; a homogeneous union. --Macaulay.
      [1913 Webster]

WordNet (r) 3.0 (2006):

amalgamation
    n 1: the combination of two or more commercial companies [syn:
         amalgamation, merger, uniting]