The Collaborative International Dictionary of English v.0.48:

Intermediate \In`ter*me"di*ate\, n.
   1. A person who intermediates between others, especially in
      negotiations; an intermediary; a mediator.
      [PJC]

   2. Something that is intermediate.
      [PJC]

   3. Specifically: (Chem.) A compound which is produced in the
      course of a chemical synthesis, which is not itself the
      final product, but is used in further reactions which
      produce the final product; also called synthetic
      intermediate, intermediate compound or intermediate
      product; -- contrasted to starting material and end
      product or final product. There may be many different
      intermediates between the starting material and end
      product in the course of a complex synthesis; as, many
      industrial chemicals are produced primarily to be used as
      intermediates in other syntheses.

   Note: The term has the same meaning with respect to
         intermediate compounds produced in a biosynthetic
         pathway in living organisms.
         [PJC]