Source : Webster's Revised Unabridged Dictionary (1913)

Propagation \Prop`a*ga"tion\, n. [L. propagatio: cf. F.
   propagation.]
   1. The act of propagating; continuance or multiplication of
      the kind by generation or successive production; as, the
      propagation of animals or plants.

            There is not in nature any spontaneous generation,
            but all come by propagation.          --Ray.

   2. The spreading abroad, or extension, of anything;
      diffusion; dissemination; as, the propagation of sound;
      the propagation of the gospel. --Bacon.

Source : WordNet®

propagation
     n 1: the spreading of something (a belief or practice) into new
          regions [syn: {extension}]
     2: the act of producing offspring or multiplying by such
        production [syn: {generation}, {multiplication}]
     3: the movement of a wave through a medium