The phrase "most overbold" refers to someone who is excessively daring or impudent. Antonyms for this phrase would include words like cautious, timid, meek, reserved, or shy. These are words that describe someone who is less likely to take risks or act boldly. Other antonyms for "most overbold" might include polite, respectful, or deferential, all of which imply a greater concern for propriety and social norms. Someone who is "most overbold" might be considered reckless, cocky, or arrogant, while the antonyms for this phrase describe individuals who are more measured and thoughtful in their approach to life.