noun · no longer timely, fresh, or interesting, especially in reference to news or information

在这个信息爆炸的时代，早晨的新闻到晚上就成了明日黄花。

noun · a person or thing that has lost its peak or relevance; something that is no longer fashionable or useful

曾经风靡一时的这种发型，现在已经是明日黄花了。