Hi Mino,
Nice to see you back on the site.
Your question is kind of a difficult one. Of course, in Latin, pro/pre = before and scribe = write. Therefore the meaning of proscribe should be to write in advance. Yet most of the dictionaries define it as to prohibit or ban sth. I haven't found the reason for it yet.
Let check these out:
http://onelook.com/?w=proscribe&ls=ahttp://www.etymonline.com/index.php?term=proscribeNote: If
proscribe means to write beforehand, what does
prescribe mean?
Will be right back
It's me
PS.
http://www.askoxford.com/concise_oed/proscribe?view=uk