unyielding (EN)
adjective

adjective “unyielding”

unyielding
  1. (of a person's behavior) firm; unwilling to give up
    Despite hours of debate, her stance on the issue remained unyielding.
  2. (of a thing) not bending or moving under pressure
    The unyielding steel door refused to budge, even after several attempts to force it open.