barbarous
adjective /ˈbɑːbərəs/
  /ˈbɑːrbərəs/
(formal)- extremely cruel and making you feel shocked
- the barbarous treatment of these prisoners of war
 
 - showing a lack of education and good manners
 
Word Originlate Middle English ((in sense 2)): via Latin from Greek barbaros ‘foreign’ + -ous.