Wack is an adjective used to describe something that is silly, absurd, or foolish. It is often used to describe a situation or behavior that is considered odd or out of place. The opposite of wack can be a few different things depending on the context. If wack is being used to describe behavior that is excessive or too much, the opposite may be something like restrained or reserved. If wack is meant to describe something that is out of touch with reality, the opposite might be grounded or practical. Ultimately, the antonyms for the word wack will depend on the specific context in which it is being used.