Source : Webster's Revised Unabridged Dictionary (1913)

Synthesis \Syn"the*sis\, n.; pl. {Syntheses}. [L., a mixture,
   properly, a putting together, Gr. ?, fr. ? to place or put
   together; sy`n with + ? to place. See {Thesis}.]
   1. Composition, or the putting of two or more things
      together, as in compounding medicines.

   2. (Chem.) The art or process of making a compound by putting
      the ingredients together, as contrasted with analysis;
      thus, water is made by synthesis from hydrogen and oxygen;
      hence, specifically, the building up of complex compounds
      by special reactions, whereby their component radicals are
      so grouped that the resulting substances are identical in
      every respect with the natural articles when such occur;
      thus, artificial alcohol, urea, indigo blue, alizarin,
      etc., are made by synthesis.

   3. (Logic) The combination of separate elements of thought
      into a whole, as of simple into complex conceptions,
      species into genera, individual propositions into systems;
      -- the opposite of {analysis}.

            Analysis and synthesis, though commonly treated as
            two different methods, are, if properly understood,
            only the two necessary parts of the same method.
            Each is the relative and correlative of the other.
                                                  --Sir W.
                                                  Hamilton.

Source : WordNet®

synthesis
     n 1: the process of producing a chemical compound (usually by the
          union of simpler chemical compounds)
     2: the combination of ideas into a complex whole [syn: {synthetic
        thinking}] [ant: {analysis}]
     3: reasoning from the general to the particular (or from cause
        to effect) [syn: {deduction}, {deductive reasoning}]
     [also: {syntheses} (pl)]

syntheses
     See {synthesis}