I have learned how to translate "можно" in phrases (e.g. with "it is possible", "one can", "it can be (done)").
However, I would like to know the actual grammatical role of the word.
My conjecture is the following:
It is an adjective singular neutrum that simply means "possible", but which is no longer used outside this kind of phrase, but still exists in composite adjectives like возмо́жный.
I would like to know if this is right and if it indeed comes from an older adjective no longer in common use.