The Collaborative International Dictionary of English v.0.48:

Muddy \Mud"dy\, v. t. [imp. & p. p. Muddied; p. pr. & vb. n.
   Muddying.]
   1. To soil with mud; to dirty; to render turbid.
      [1913 Webster]

   2. (Fig.): To cloud; to make dull or heavy; to confuse.
      --Grew.
      [1913 Webster]