WordNet sense 1 (unshaken in purpose):

undaunted, unshaken

WordNet sense 2 (determined):

resolved

WordNet sense 3 (marked by firm determination or resolution; not shakable):

firm, steadfast, steady, unwavering

WordNet sense 4 (characterized by great determination):

determined

WordNet sense 5 (characterized by quickness and firmness):

unhesitating