The Collaborative International Dictionary of English v.0.48:

Foggy \Fog"gy\, a. [Compar. Foggier; superl. Foggiest.]
   [From 4th Fog.]
   1. Filled or abounding with fog, or watery exhalations;
      misty; as, a foggy atmosphere; a foggy morning. --Shak.
      [1913 Webster]

   2. Beclouded; dull; obscure; as, foggy ideas.
      [1913 Webster]

            Your coarse, foggy, drowsy conceit.   --Hayward.
      [1913 Webster]