DuckCorp Dico

Found one definition

1.                 From The Collaborative International Dictionary of English v.0.48:
                   
   
   
                   
                     
   Plowshare \Plow"share`\, Ploughshare \Plough"share"\, n.
      The share of a plow, or that part which cuts the slice of
      earth or sod at the bottom of the furrow.
      [1913 Webster]
      Plowshare bone (Anat.), the pygostyle.
         [1913 Webster] Plowtail