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.

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.

Overflow \O`ver*flow"\, v. i.
   1. To run over the bounds.

   2. To be superabundant; to abound. --Rogers.

Source : WordNet®

overflow
     n 1: a large flow [syn: {flood}, {outpouring}]
     2: the occurrence of surplus liquid (as water) exceeding the
        limit or capacity [syn: {runoff}, {overspill}]
     v 1: flow or run over (a limit or brim) [syn: {overrun}, {well
          over}, {run over}, {brim over}]
     2: overflow with a certain feeling; "The children bubbled over
        with joy"; "My boss was bubbling over with anger" [syn: {bubble
        over}, {spill over}]
     [also: {overflown}]