The phrase "under one thumb" denotes a person who is excessively dominated or controlled by another, implying a lack of individuality, independence or freedom. Antonyms for this phrase would, therefore, include words and phrases that describe empowerment, autonomy, and self-assurance. These antonyms include "free-spirited," "self-sufficient," "independent," "assertive," "confident," and "self-reliant." Such contrasting words could help to encourage a sense of personal growth and self-worth, promoting the idea that one should not be held down or restricted by the control of others. By emancipating themselves from such limiting beliefs, individuals can achieve a sense of personal fulfillment and liberation.