pertinacious
definition
holding firm to an opinion or course of action stubbornly
example
Despite facing numerous challenges, her pertinacious determination to achieve her goals inspired everyone around her.
synonyms
persistenttenaciousresolute
word origin — From Latin 'pertinax', meaning 'holding fast' or 'obstinate'; from 'per-' (through) + 'tinere' (to hold).