faithless elector
member of the U.S. Electoral College who does not vote for the candidate for whom they had pledged to vote
en-US/ˈfeɪθlɪs ɪˈlɛktɚ/
en-GB/ˈfeɪθlɪs ɪˈlɛktə/
member of the U.S. Electoral College who does not vote for the candidate for whom they had pledged to vote