The word "un-determined" denotes a state of uncertainty or absence of a decision. The antonyms of "un-determined" are a group of words that convey certainty or a decisive state. Among the antonyms, terms like decisive, confirmed, decisive, certain, firm, and resolute are commonly used. Decisive implies having the ability to make decisions and taking quick action on them. Similarly, confirmed suggests a clear understanding or acceptance of a concept or idea. On the other hand, firm and resolute reflect the steadfastness and determination of an individual in their decision-making process. In contrast, indecisive, uncertain, and ambiguous are among the synonymous terms for "un-determined.