The Collaborative International Dictionary of English v.0.48:

Emission \E*mis"sion\, n. [L. emissio: cf. F. ['e]mission. See
   Emit.]
   1. The act of sending or throwing out; the act of sending
      forth or putting into circulation; issue; as, the emission
      of light from the sun; the emission of heat from a fire;
      the emission of bank notes.
      [1913 Webster]

   2. That which is sent out, issued, or put in circulation at
      one time; issue; as, the emission was mostly blood.
      [1913 Webster]

   Emission theory (Physics), the theory of Newton, regarding
      light as consisting of emitted particles or corpuscles.
      See Corpuscular theory, under Corpuscular.
      [1913 Webster]