Be in doubt Definition 1 of 2Pro Tip 1/3Personal Uncertainty Use when expressing personal hesitation or lack of conviction. I'm in doubt about my ability to run a marathon. Pro Tip 2/3Expect Contradiction Signals you are open to other opinions or information that may change your mind. I think he's right, but I'm still in doubt. Pro Tip 3/3Decision Making Often used when someone is trying to make a choice but needs more information. She was in doubt about which college to attend.