oppositional
adjective /ˌɒpəˈzɪʃənl/
  /ˌɑːpəˈzɪʃənl/
 [usually before noun] (formal)- strongly disagreeing with somebody/something- oppositional groups
- The party had tried to exclude all oppositional voices.
 
- as different as possible from one another- two quite different and somewhat oppositional stances