The Collaborative International Dictionary of English v.0.48:

Muddle \Mud"dle\, v. t. [imp. & p. p. Muddled; p. pr. & vb. n.
   Muddling.] [From Mud.]
   1. To make turbid, or muddy, as water. [Obs.]
      [1913 Webster]

            He did ill to muddle the water.       --L'Estrange.
      [1913 Webster]

   2. To cloud or stupefy; to render stupid with liquor; to
      intoxicate partially.
      [1913 Webster]

            Epicurus seems to have had brains so muddled and
            confounded, that he scarce ever kept in the right
            way.                                  --Bentley.
      [1913 Webster]

            Often drunk, always muddled.          --Arbuthnot.
      [1913 Webster]

   3. To waste or misuse, as one does who is stupid or
      intoxicated. [R.]
      [1913 Webster]

            They muddle it [money] away without method or
            object, and without having anything to show for it.
                                                  --Hazlitt.
      [1913 Webster]

   4. To mix confusedly; to confuse; to make a mess of; as, to
      muddle matters; also, to perplex; to mystify. --F. W.
      Newman.
      [1913 Webster]

WordNet (r) 3.0 (2006):

muddled
    adj 1: confused and vague; used especially of thinking;
           "muddleheaded ideas"; "your addled little brain"; "woolly
           thinking"; "woolly-headed ideas" [syn: addled,
           befuddled, muddled, muzzy, woolly, wooly,
           woolly-headed, wooly-minded]

Moby Thesaurus II by Grady Ward, 1.0:

111 Moby Thesaurus words for "muddled":
   addlebrained, addled, addleheaded, addlepated, anarchic,
   arsy-varsy, ass-backwards, at a loss, baffled, balled up,
   bamboozled, beat, beclouded, beery, befuddled, bemused, besotted,
   blear-witted, blind drunk, bollixed up, boozy, buffaloed, canned,
   chaotic, cloudy, confounded, confused, crapulent, crapulous, dazed,
   disconnected, discontinuous, disguised, disjointed, disordered,
   dizzy, drenched, drunk, drunken, far-gone, floored, flustered,
   fogged, foggy, fou, fouled up, fuddlebrained, fuddled, full,
   galley-west, gay, giddy, glorious, happy, hazy, helter-skelter,
   higgledy-piggledy, hugger-mugger, in a dilemma, in a fog,
   in a mess, in a muddle, in liquor, in suspense, inchoate,
   inebriate, inebriated, inebrious, intoxicated, jolly, jumbled,
   licked, maudlin, mellow, merry, misted, misty, mixed up, mucked up,
   muddleheaded, muddybrained, muzzy, mystified, nappy, nonplussed,
   on tenterhooks, perplexed, pixilated, plastered, puzzled,
   puzzleheaded, reeling, scattered, scramblebrained, screwed up,
   shikker, skimble-skamble, snafu, sodden, sotted, stuck, stumped,
   thrown, tiddly, tight, tipsy, topsy-turvy, unconnected,
   under the influence, unorganized, upside-down