skep·tic (US) or Brit scep·tic 
/ˈskɛptɪk/ noun
plural skep·tics /ˈskɛptɪk/ noun [count] : a person who questions or doubts something (such as a claim or statement)
▪ Skeptics have pointed out flaws in the researchers' methods. ▪ You can believe in ghosts if you like, but I'm still a skeptic. : a person who often questions or doubts things ▪ He is a skeptic and a cynic.
▪ Skeptics have pointed out flaws in the researchers' methods. ▪ You can believe in ghosts if you like, but I'm still a skeptic. : a person who often questions or doubts things ▪ He is a skeptic and a cynic.
