Longman Dictionary of Contemporary English - forbidden

~ adj 1 not allowed, especially because of an official rule  (strictly forbidden)  (You can't smoke here - it's strictly forbidden. | it is forbidden to do sth)  (It is forbidden to marry someone who is not a member of the same faith.) 2 a forbidden place is one that you are not allowed to go to  (the Great Mosque, whose precincts are forbidden to Christians) 3 a forbidden activity, object etc is one that seems exciting because you are not allowed to do it or have it  (the forbidden sensual pleasures of the old city | forbidden fruit (=something forbidden that gives great pleasure))