Which must mean the opposite of good?

This is a bit of a trick question! There's no single word that *must* mean the opposite of good. It depends on the context. Here's why:

* Good and Evil: This is the most common and classic pairing. "Evil" is often considered the direct opposite of good, especially in moral or ethical discussions.

* Good and Bad: This is another very common pairing. "Bad" is generally a less extreme opposite than "evil," and can refer to things that are simply not good, rather than actively harmful.

* Good and Other Specific Opposites: Depending on the specific meaning of "good", the opposite could be:

* Bad: For things like quality, e.g., "good wine" vs. "bad wine".

* Ugly: For things like aesthetics, e.g., "good looks" vs. "ugly looks".

* Incorrect: For things like truth, e.g., "good answer" vs. "incorrect answer".

So, there isn't one definitive answer. The best way to figure out the opposite of "good" is to consider the context of the sentence or situation.