|a person who insists on proof before he will believe anything; sceptic|
|an extraordinary or unusual thing, person, or event; an exceptional example or instance.|
|a chattering or flighty, light-headed person.|
One who is habitually doubtful. For example, He was a doubting Thomas about the coming merger, not believing it would ever happen. The term alludes to the disciple Thomas, who doubted Jesus's resurrection until he had first-hand evidence of it (John 20:24-29).