Resolute
/ˈrɛz.ə.luːt/ adjective easyFirmly determined and unlikely to change course despite pressure or difficulty.
Despite three rejections, she remained resolute in her plan to reapply to medical school.
Memory Trick
Think of it as 're-solved-and-set' — a resolute person has already solved the question of what to do and will not reopen the case.