Source : Webster's Revised Unabridged Dictionary (1913)

Overflow \O`ver*flow"\, v. t. [imp. & p. p. {Overflowed}; p. pr.
   & vb. n. {Overflowing}.] [AS. oferfl?wan. See {Over}, and
   {Flow}.]
   1. To flow over; to cover woth, or as with, water or other
      fluid; to spread over; to inundate; to overwhelm.

            The northern nations overflowed all Christendom.
                                                  --Spenser.

   2. To flow over the brim of; to fill more than full.