that cannot be moved; not able, refusing to be affected or changed

fixed, stubborn

not easily agreeing to an argument or being persuaded; stubborn

stubborn, determined

without pity (and determined)

cruel, merciless

very determined

determined, strong-willed

decided and fixed; (of opinions, habits etc) fixed and not to be changed; unmoving; a group of games (in tennis etc); a group of similar things; the position (of the body, clothes etc)

decided

strong and determined; a loyal supporter

strong, valiant

(of rules) strict, severe; that must be obeyed

rigid, tight

not hesitating

steadfast

not becoming less in force, degree

merciless