The word "unfitting" signifies something that is not appropriate or unsuitable for a particular situation. Some possible antonyms for "unfitting" include "appropriate," "suitable," "fitting," and "proper." These words imply that something is well-suited to a given context, or that it conforms to the standards or expectations of that context. Other antonyms for "unfitting" might include "well-matched," "compatible," "harmonious," or "perfect." These words suggest that something is ideally suited to its environment or complements other elements within that environment seamlessly. Ultimately, the right antonym for "unfitting" will depend on the specific context in which the term is being used.