Nonplused

from WordNet (r) 3.0 (2006)

nonplused
    adj 1: filled with bewilderment; "at a loss to understand those
           remarks"; "puzzled that she left without saying goodbye"
           [syn: {at a loss(p)}, {nonplused}, {nonplussed},
           {puzzled}]

from The Collaborative International Dictionary of English v.0.48

Nonplus \Non"plus`\, v. t. [imp. & p. p. {Nonplused}or
   {Nonplussed}; p. pr. & vb. n. {Nonplusing} or {Nonplussing}.]
   To puzzle; to confound; to perplex; to cause to stop by
   embarrassment.
   [1913 Webster]

         He has been nonplused by Mr. Dry's desiring him to tell
         what it was that he endeavored to prove. --Spectator.
   [1913 Webster]