When we want to describe something that is not quite right or not suitable for its intended purpose, we often use the phrase "not the thing". However, there are several synonyms that can be used to convey the same meaning. For instance, we can say something is inappropriate, unsuitable, or incongruous. We could say that it is off the mark, off the beam, or off the cuff. We could also describe it as ill-fitting, misplaced, or out of place. These synonyms can help us to express ourselves more effectively, and to communicate our thoughts and feelings more precisely.