The phrase "altogether forbidden" is correct and can be used in written English.
It is commonly used to describe something that is completely prohibited or not allowed at all. Example: Smoking is altogether forbidden on the school premises.
To anyone not in the know, the prospect might have seemed stern if not altogether forbidding: a full evening of a cappella singing by the Moscow Sretensky Monastery Choir.
He said that although the medical testimony was somewhat equivocal, the court accepted the view that "a statute that altogether forbids D & X creates a significant health risk" and would be unconstitutional for that reason alone.
One of the few times kissing was forbidden altogether was during a cholera outbreak in 1973.
In a footnote of its terms, however, Verizon explained that although e-mail, web browsing and remote corporate activities were not subject to limits, streaming and downloading any media was forbidden altogether.
It was forbidden and altogether exciting territory and I dived in without a care in the world – if it was the kind of story that my media house was willing to publish, then why not?
Local ordinances call on homeowners to turn off their outdoor lights at night, and white lights are forbidden on the beach altogether.
This turn to technology, however, is not devoid of religious aspects: although dying in battle is undisputedly holy, many scholars claim that any intentional taking of one's own life is forbidden, thus outlawing suicide attacks altogether.
In the same year, however, they were forbidden to perform religious plays and gradually gave up acting altogether, preferring to lease the theatre to traveling companies.
Islam forbids it altogether.
