oppositional

From opposition + -al.

oppositional (comparative more oppositional, superlative most oppositional)

1. Of, pertaining to, or exhibiting opposition.
   • 2007 March 10, Steven Lee Myers, “Kasparov, Building Opposition to Putin”, in New York Times‎^[1]:

     And he has brought to oppositional politics the same energy and aggression that characterized his chess, attacking Mr. Putin and the Kremlin — or the regime, as he repeatedly calls it — with language rarely spoken so bluntly in Russia.