skepticism (n.)

• agnosticism
• apprehension
• caution
• cautiousness
• concern
• diffidence
• distrust
• distrustfulness
• doubt
• doubtfulness
• dubiety
• dubiousness
• incertitude
• incredulity
• misgiving
• mistrust
• qualm
• question
• scoffing
• scruple
• scrupulousness
• self-doubt
• suspicion
• suspiciousness
• uncertainty
• wariness
• wonder