The Collaborative International Dictionary of English v.0.48:

Overhear \O`ver*hear"\, v. t. [imp. & p. p. Overheard; p. pr.
   & vb. n. Overhearing.] [AS. oferhi['e]ran.]
   [1913 Webster]
   1. To hear more of (anything) than was intended to be heard;
      to hear by accident or artifice. --Shak.
      [1913 Webster]

   2. To hear again. --Shak.
      [1913 Webster]