The Collaborative International Dictionary of English v.0.48:

Ferret \Fer"ret\, v. t. [imp. & p. p. Ferreted; p. pr. & vb.
   n. Ferreting.] [Cf. F. fureter. See Ferret, n.]
   To drive or hunt out of a lurking place, as a ferret does the
   cony; to search out by patient and sagacious efforts; --
   often used with out; as, to ferret out a secret.
   [1913 Webster]

         Master Fer! I'll fer him, and firk him, and ferret him.
                                                  --Shak.
   [1913 Webster]