Source : Webster's Revised Unabridged Dictionary (1913)

Overflow \O"ver*flow`\, n.
   1. A flowing over, as of water or other fluid; an inundation.
      --Bacon.

   2. That which flows over; a superfluous portion; a
      superabundance. --Shak.

   3. An outlet for the escape of surplus liquid.

   {Overflow meeting}, a meeting constituted of the surplus or
      overflow of another audience.