The opposite of "un-related" could be "related." In this context, it means that two or more things are connected or have some sort of relationship. Another antonym for "un-related" could be "associated" which means being connected or linked with something else. If two things are seen as opposite or in contrast to each other, then "related" could be the antonym for "un-related." If something is "un-related," it means that it is not connected, linked, associated, or relevant. Knowing the antonyms of words helps to understand and contextualize their meanings in different scenarios.