uncompromising

Etymology

un- + compromising

adj

1. Inflexible and unwilling to negotiate or make concessions.
   But Richmond, his grandfather's darling, after one thoughtful glance cast under his lashes at that uncompromising countenance appeared to lose himself in his own reflections. 1959, Georgette Heyer, chapter 1, in The Unknown Ajax
   The visitors, who surprisingly dropped their talismanic record goalscorer Robbie Keane from their starting line-up for a competitive game for the first time in 13 years, adopted a direct and uncompromising approach. November 14, 2014, Stephen Halliday, “Scotland 1-0 Republic of Ireland: Maloney the hero”, in The Scotsman
2. Principled.