Antonyms for the term "most self-determining" could be "dependent," "unassertive," "submissive," "passive," or "timid." These terms signify a lack of autonomy and the inability to make decisions independently. In contrast, "self-determining" implies a person who is independent, assertive, and capable of making choices that align with their values and beliefs. Synonyms for the term could include "autonomous," "self-governing," "self-regulating," or "self-reliant." Ultimately, being self-determining is a coveted trait as it implies a strong sense of agency and the ability to chart one's course in life.