The Collaborative International Dictionary of English v.0.48:

Filthy \Filth"y\, a. [Compar. Filthier; superl. Filthiest.]
   Defiled with filth, whether material or moral; nasty; dirty;
   polluted; foul; impure; obscene. "In the filthy-mantled
   pool." --Shak.
   [1913 Webster]

         He which is filthy let him be filthy still. --Rev.
                                                  xxii. 11.

   Syn: Nasty; foul; dirty; squalid; unclean; sluttish; gross;
        vulgar; licentious. See Nasty.
        [1913 Webster]