"Kept under thumb" commonly refers to someone who is controlled or dominated by another person. Some antonyms for this phrase could be "independent," "free," "autonomous," "self-determining," "self-governing," "liberated," or "unrestricted." These words suggest an individual's ability to make decisions for themselves and to be in control of their own life. By using these antonyms instead of the negative phrase "kept under thumb," we can empower individuals and promote the idea of autonomy and freedom. It is important to recognize the value of personal agency and foster a society where individuals are allowed to thrive independently.