The Collaborative International Dictionary of English v.0.48:

Embayment \Em*bay"ment\, n.
   A bay. [R.]
   [1913 Webster]

         The embayment which is terminated by the land of North
         Berwick.                                 --Sir W.
                                                  Scott.
   [1913 Webster]

WordNet (r) 3.0 (2006):

embayment
    n 1: an indentation of a shoreline larger than a cove but
         smaller than a gulf [syn: bay, embayment]