fateful
adjective [ before noun ] uk/ˈfeɪt.fəl/ us/ˈfeɪt.fəl/
对未来有重大（负面）影响的
having an important and usually negative effect on the future
the fateful day of President Kennedy's assassination 肯尼迪总统遇刺的灾难性的一天
He made the fateful decision to send in the troops. 他作出了派遣部队这个影响重大的决定。