no longer new or fresh, usually as a result of being kept for too long

The bread/biscuits/cake had gone stale. 面包／饼干／蛋糕已经不新鲜了。

The morning after the party, their apartment smelled of stale cigarette smoke. 聚会后的次日早上，他们的公寓里有一股污浊的烟味儿。

not fresh and new; boring because too familiar

stale jokes/news 老掉牙的笑话／过时的新闻

used to describe someone who has lost interest in what they are doing because of being bored or working too hard

They had been working together for over five years and they had both become a little stale. 他们两个已经在一起共事5年多了，彼此都有一点儿厌倦。