The Collaborative International Dictionary of English v.0.48:

puzzle \puz"zle\, v. t. [imp. & p. p. puzzled (p[u^]z"z'ld);
   p. pr. & vb. n. puzzling (p[u^]z"zl[i^]ng).]
   1. To perplex; to confuse; to embarrass; to put to a stand;
      to nonplus.
      [1913 Webster]

            A very shrewd disputant in those points is dexterous
            in puzzling others.                   --Dr. H. More.
      [1913 Webster]

            He is perpetually puzzled and perplexed amidst his
            own blunders.                         --Addison.
      [1913 Webster]

   2. To make intricate; to entangle.
      [1913 Webster]

            They disentangle from the puzzled skein. --Cowper.
      [1913 Webster]

            The ways of Heaven are dark and intricate,
            Puzzled in mazes, and perplexed with error.
                                                  --Addison.
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   3. To solve by ingenuity, as a puzzle; -- followed by out;
      as, to puzzle out a mystery.
      [1913 Webster]

   Syn: To embarrass; perplex; confuse; bewilder; confound. See
        Embarrass.
        [1913 Webster]

WordNet (r) 3.0 (2006):

puzzling
    adj 1: not clear to the understanding; "I didn't grasp the
           meaning of that enigmatic comment until much later";
           "prophetic texts so enigmatic that their meaning has been
           disputed for centuries" [syn: enigmatic, enigmatical,
           puzzling]
    2: lacking clarity of meaning; causing confusion or perplexity;
       "sent confusing signals to Iraq"; "perplexing to someone who
       knew nothing about it"; "a puzzling statement" [syn:
       confusing, perplexing, puzzling]

Moby Thesaurus II by Grady Ward, 1.0:

83 Moby Thesaurus words for "puzzling":
   able, abstruse, ambiguous, baffling, beguiling, bewildering,
   bothering, confounding, confusing, contradictory, cryptic,
   discomposing, disconcerting, dismaying, distracting, disturbing,
   embarrassing, enigmatic, enigmatical, exceptional, extraordinary,
   fabulous, fantastic, fascinating, incalculable, incognizable,
   incomprehensible, inconceivable, incredible, intricate, marvelous,
   miraculous, mysterious, mystifying, outlandish, passing strange,
   perplexing, perturbing, phenomenal, problematic, prodigious, rare,
   remarkable, riddling, sealed, sensational, sphinxlike, strange,
   striking, stupendous, unapparent, unapprehended, unascertained,
   unbeknown, uncharted, unclassified, undisclosed, undiscoverable,
   undiscovered, undivulged, unexplained, unexplored, unexposed,
   unfamiliar, unfathomed, unheard, unheard-of, unidentified,
   unimaginable, uninvestigated, unique, unknowable, unknown,
   unperceived, unplumbed, unprecedented, unrevealed, unsuspected,
   untouched, upsetting, virgin, wonderful, wondrous