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]

WordNet (r) 3.0 (2006):

foggy
    adj 1: stunned or confused and slow to react (as from blows or
           drunkenness or exhaustion) [syn: dazed, foggy,
           groggy, logy, stuporous]
    2: indistinct or hazy in outline; "a landscape of blurred
       outlines"; "the trees were just blurry shapes" [syn:
       bleary, blurred, blurry, foggy, fuzzy, hazy,
       muzzy]
    3: filled or abounding with fog or mist; "a brumous October
       morning" [syn: brumous, foggy, hazy, misty]
    4: obscured by fog; "he could barely see through the fogged
       window" [syn: fogged, foggy]

Moby Thesaurus II by Grady Ward, 1.0:

102 Moby Thesaurus words for "foggy":
   addlebrained, addled, addleheaded, addlepated, aleatoric, aleatory,
   amorphous, beclouded, befuddled, blear, blear-witted, bleared,
   bleary, blind, blobby, blurred, blurry, broad, chance, chancy,
   chaotic, clear as mud, cloudy, confused, dark, dim, disordered,
   dizzy, faint, feeble, filmy, fogged, fuddlebrained, fuddled, fuzzy,
   general, half-seen, half-visible, hazy, hit-or-miss, ill-defined,
   imprecise, in a fog, in a muddle, inaccurate, inchoate, incoherent,
   inconspicuous, indecisive, indefinable, indefinite, indeterminable,
   indeterminate, indistinct, indistinguishable, inexact, lax, loose,
   low-profile, merely glimpsed, misted, misty, muddled, muddleheaded,
   muddy, muddybrained, murky, mushy, muzzy, nebulous, nonspecific,
   obscure, opaque, orderless, out of focus, pale, pea-soupy,
   puzzleheaded, random, scramblebrained, semivisible, shadowed forth,
   shadowy, shapeless, smoggy, soupy, stochastic, sweeping,
   transcendent, uncertain, unclear, undefined, undestined,
   undetermined, unplain, unrecognizable, unspecified, vague,
   vaporous, vapory, veiled, weak