Humism, Pyrrhonism, agnosticism, apprehension, caution, cautiousness, concern, diffidence, disinclination to believe, distrust, distrustfulness, doubt, doubtfulness, dubiety, dubiousness, guardedness, half-belief, incertitude, inconvincibility, incredulity, leeriness, misdoubt, misgiving, mistrust, mistrustfulness, qualm, qualmishness, question, resistiveness to belief, scoffing, scruple, scrupulousness, self-doubt, shadow of doubt, skepticalness, suspicion, suspiciousness, total skepticism, tough-mindedness, uncertainty, unconvincibility, uncredulousness, unpersuadability, unpersuasibility, wariness, wonder