The Collaborative International Dictionary of English v.0.48:

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.
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            That Power who bids the ocean ebb and flow. --Pope.
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   2. To return or fall back from a better to a worse state; to
      decline; to decay; to recede.
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            The hours of life ebb fast.           --Blackmore.

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