When someone "has doubt" about something, they are uncertain or skeptical about its validity or accuracy. There are several synonyms for this phrase, including: questioning, hesitating, second-guessing, doubting, mistrusting, and suspecting. When someone is questioning something, they are unsure and seeking clarification. When someone is hesitating, they are pausing before making a decision because they are not confident. When someone is second-guessing, they are reconsidering a decision they have already made. When someone is doubting, they are skeptical and hesitant to believe. When someone is mistrusting, they do not fully trust or have confidence. Lastly, when someone is suspecting, they have a feeling or belief that something is not right.