something that is considered to be a sign of how a future event will take place

The team's final victory of the season is a good omen for the playoffs, which start next week. 球队在本赛季最后一场比赛中获得胜利，这对下星期就开始的季后加赛来说是一个好兆头。

a bad omen 坏兆头

Many people believe that a broken mirror is an omen of bad luck. 许多人相信打碎镜子是噩运之兆。