overhear

from WordNet (r) 3.0 (2006)

overhear
    v 1: hear, usually without the knowledge of the speakers; "We
         overheard the conversation at the next table" [syn:
         {catch}, {take in}, {overhear}]

from 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]