Doubt

Doubt is a feeling of distrust, anxiety or disbelief. The sentiment depends the tone and context of the speaker. Example: #1) I have some doubts about the success of our project. (anxiety) #2) Michael said that he was coming to the event, but I doubt he will come. (disbelief) #3) I have a few doubts about the new employee, but the manager seems to trust him. (distrust)

Self-doubt is when a person doesn't wholly believe in the correctness of their decisions and actions. Example: Since his divorce, David has been afraid to make any decisions. He is filled with self-doubt and over-analyzes everything. It's difficult to talk to him and I'm convinced he will die a lonely old man. I hope his ex-wife is happy with her new husband because it turned David into a self-doubting, unapproachable and unpleasant person, who can never love again.

"I doubt it" is a response to an assertion or question you don't believe is likely. Example: #1) "I heard that David stopped drinking." "I doubt it." #2) "Do you think true love is possible within or lifetime?" "I doubt it."

Doubtful is used to describe a situation that doesn't look hopeful. Example: #1) My kids want to go to Dizneyland this summer, but it's doubtful that I can afford it. #2) My kids want to go to university, but it's doubtful that they can get good enough grades. #3) My daughter wants to marry someday, but it's doubtful any man would be interested in her.

Dubious is used to describe a situation that may be different than it appears on the surface. It is a term to express suspicion. Example: #1) The carpenter told me he was an expert, but the quality of his work is dubious. #2) The man told me he didn't know the killer, but his claims are dubious.