sceptical

from WordNet (r) 3.0 (2006)

sceptical
    adj 1: marked by or given to doubt; "a skeptical attitude"; "a
           skeptical listener" [syn: {doubting}, {questioning},
           {skeptical}, {sceptical}]
    2: denying or questioning the tenets of especially a religion;
       "a skeptical approach to the nature of miracles" [syn:
       {disbelieving}, {skeptical}, {sceptical}, {unbelieving}]

from The Collaborative International Dictionary of English v.0.48

Sceptic \Scep"tic\, Sceptical \Scep"tic*al\, Scepticism
\Scep"ti*cism\, etc.
   See {Skeptic}, {Skeptical}, {Skepticism}, etc.
   [1913 Webster]