The concept of having a "made up mind" implies that one has made a firm decision about something. Antonyms for this phrase could include indecisive, unsure, undecided, or ambivalent. People who are indecisive may struggle to make a decision, or may change their minds frequently. Those who are unsure may lack the confidence to commit to a particular course of action. Individuals who are undecided may be weighing pros and cons, while those who are ambivalent may feel conflicted about a decision or unable to choose between two options. In contrast, having a "flexible" or "open" mind suggests a willingness to consider alternative viewpoints or to change one's opinion when presented with new information.