the vote given by the person in charge of an official meeting to decide an issue when votes on each side are equal （会议主席在赞成票和反对票票数相等时所投的）决定票 You have the casting vote. 你有决定性的一票。 The chairman gave his casting vote in favour. 主席投了赞成票。
Word Originearly 17th cent.: from an obsolete sense of cast ‘turn the scale’.