The term 'well-suited' refers to a perfect match or a good fit. The opposite of well-suited is 'ill-suited,' which means not well-matched or not a good fit. Ill-suited could also be interpreted as mismatched, unsuitable, inappropriate or incompatible. In addition, the term 'improper' would be a good antonym for well-suited. If an object, person, or situation is not well-matched or has contrasting properties, then it is not considered to be well-suited. The term 'misaligned' is another antonym for well-suited, which refers to something that is not in sync or mismatched. Overall, there are various antonyms for the word 'well-suited' that describe different aspects of a situation or object not being a perfect match.