Most offbeam is a phrase that refers to something that is way off course or completely wrong. Its antonyms could be "accurate," "correct," "appropriate," "suitable," "proper," or "right." These words suggest that something is on target or in line with expectations. Other antonyms for "most offbeam" might include "relevant," "timely," "pertinent," "valid," or "helpful." All of these words connote that something is useful, helpful, and applicable to a particular situation. It's important to note that the opposite of "most offbeam" depends on the context, and the best choice of an antonym will depend on the situation.