doubt

(noun) the state of being unsure of something. Synonyms: uncertainty, incertitude, dubiety, doubtfulness, dubiousness.

(noun) uncertainty about the truth or factuality or existence of something. Synonyms: dubiousness, doubtfulness, question. Examples: "The dubiousness of his claim." "There is no question about the validity of the enterprise."

(verb) consider unlikely or have doubts about. Example: "I doubt that she will accept his proposal of marriage."

(verb) lack confidence in or have doubts about. Examples: "I doubt these reports." "I suspect her true motives." "She distrusts her stepmother."