Source : Webster's Revised Unabridged Dictionary (1913)

Ebb \Ebb\, v. i. [imp. & p. p. {Ebbed}; p. pr. & vb. n.
   {Ebbing}.] [AS. ebbian; akin to D. & G. ebben, Dan. ebbe. See
   2d {Ebb}.]
   1. To flow back; to return, as the water of a tide toward the
      ocean; -- opposed to {flow}.

            That Power who bids the ocean ebb and flow. --Pope.

   2. To return or fall back from a better to a worse state; to
      decline; to decay; to recede.

            The hours of life ebb fast.           --Blackmore.

   Syn: To recede; retire; withdraw; decay; decrease; wane;
        sink; lower.

Source : WordNet®

ebbing
     n : a gradual decline (in size or strength or power or number)
         [syn: {ebb}, {wane}]