When expressing doubt or uncertainty, it's essential to choose the right words to accurately convey your thoughts and feelings. If you're looking for synonyms for 'in a doubtful manner,' there are several options that can help give a clearer picture of your state of mind. Some phrases to consider include 'uncertainly,' 'hesitantly,' or 'with apprehension.' Other choices might include 'indefinitely,' 'insecurely,' 'inconclusively,' or 'ambiguously.' Choosing the right synonym can help you communicate more effectively and ensure that your message is received as intended. Remember to choose words that accurately reflect your true feelings and doubts to ensure the best possible outcome.