Here are some synonyms for forbidden:
* Prohibited
* Banned
* Outlawed
* Off-limits
* Unlawful
* Restricted
* Taboo
Examples:
* "The teacher told us that using phones in class is forbidden."
* "The ancient city is forbidden to tourists."
* "Eating pork is forbidden in some religions."
* "The book was forbidden in several countries."
The meaning of "forbidden" can vary slightly depending on the context. It can also be used figuratively to express a strong sense of desire or temptation.
For example:
* "The forbidden fruit is always the sweetest."
In this case, "forbidden" refers to something that is desirable because it is out of reach.