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]

The Collaborative International Dictionary of English v.0.48:

Mousing \Mous"ing\, a.
   Impertinently inquisitive; prying; meddlesome. "Mousing
   saints." --L'Estrange.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Mousing \Mous"ing\, n.
   1. The act of hunting mice.
      [1913 Webster]

   2. (Naut.) A turn or lashing of spun yarn or small stuff, or
      a metallic clasp or fastening, uniting the point and shank
      of a hook to prevent its unhooking or straighening out.
      [1913 Webster]

   3. A ratchet movement in a loom.
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   Mousing hook, a hook with an attachment which prevents its
      unhooking.
      [1913 Webster]