The word prohibited means forbidden; banned. Many people would associate "forbidden" with "no".
For examples:
It depends on what you mean by prohibited, but the general answer is no, not legally.
Prohibited means something that is banned or forbidden, off limits. So 'not prohibited' means that it is available.
Yes, it is a adjective.
yes
Yes. Banned is another word for prohibited. Outlawed is another word for banned, or to make illegal.
yes
Ever heard of Dictionary.com?
prohibited means not allowed
yes. most of the time visiting was prohibited in POW camps.
yes
prohibited means not allowed
The word prohibited — when you see it anywhere —?always means "is not allowed", and sometimes also means "is illegal".