Which word best describes something that is unnecessary?

The term "superfluous" effectively conveys the idea of something that is unnecessary or excessive. It refers to elements that go beyond what is needed, suggesting that they do not contribute any essential value to a situation. For instance, in a conversation, adding superfluous comments may detract from the main point rather than enhance it.

In contrast, "mandatory" suggests something that is required or obligatory, indicating it is essential rather than unnecessary. "Indispensable" denotes something that cannot be done without, further emphasizing the necessity rather than the superfluity of an object or action. Similarly, "critical" implies a crucial importance, reinforcing the idea that something is vital rather than unnecessary. Therefore, "superfluous" is the most fitting choice to describe something that is not needed.