adj
not allowed, especially because of an official rule
→bannedit is forbidden (to do sth)
　It is forbidden to smoke at school.
be strictly/expressly/absolutely etc forbidden
　Alcohol is strictly forbidden in Saudi Arabia.
a forbidden place is one that you are not allowed to go to
forbidden to
　The Great Mosque is forbidden to Christians.
a forbidden activity, subject etc is one that people think that you should not do, talk about etc
　Sex was always a forbidden topic.
forbidden fruit
(=something that you should not have, but that you want)
　Forbidden fruit is always more attractive.