The Collaborative International Dictionary of English v.0.48:

Overflow \O"ver*flow`\, n.
   1. A flowing over, as of water or other fluid; an inundation.
      --Bacon.
      [1913 Webster]

   2. That which flows over; a superfluous portion; a
      superabundance. --Shak.
      [1913 Webster]

   3. An outlet for the escape of surplus liquid.
      [1913 Webster]

   Overflow meeting, a meeting constituted of the surplus or
      overflow of another audience.
      [1913 Webster]