The Collaborative International Dictionary of English v.0.48:

Mouse \Mouse\, v. i. [imp. & p. p. Moused; p. pr. & vb. n.
   Mousing.]
   1. To watch for and catch mice.
      [1913 Webster]

   2. To watch for or pursue anything in a sly manner; to pry
      about, on the lookout for something.
      [1913 Webster]