unlikely
doubtful.
doubtful, suspect
doubtful, unsavory, slippery
The root word of doubtful is "doubt."
An evil man is always doubtful. Without a doubt, Wikianswers is the best question and answer site.
"doubtful" does not have a prefix. It does, however, have a suffix ('-ful').
You can use the word "doubtful" to express uncertainty or skepticism about something. For example, "It is doubtful that we will finish the project on time," or "She gave a doubtful look at the new proposal."
doubtful
It is doubtful that the Fourth of July picnic will be cancelled due to snow.
Example sentence - It is doubtful the student will graduate as he does not have the credits required.
It is doubtful that it will rain today but take your umbrella just in case.
This is highly doubtful.