1. (食物)不新鲜的，变味的
    Stale food is no longer fresh or good to eat.

stale

    e.g. Their daily diet consisted of a lump of stale bread, a bowl of rice and stale water.
           他们的日常饮食包括一块不新鲜的面包、一碗米饭和变味的水。

2. (空气、气味)不新鲜的，污浊的
    Stale air or a stale smells is unpleasant because it is no longer fresh.

    e.g. A layer of smoke hung low in the stale air.
           一层烟雾低悬在污浊的空气中。
    e.g. ...the smell of stale sweat.
           汗臭味

3. 厌倦的;腻烦的
    If you feel stale, you are bored because you have no new ideas or enthusiasm for what you are doing.

stale的翻译

    e.g. I believe in progression, in taking risks, in never getting stale.
           我崇尚进取、冒险和永不倦怠。

4. (地方、活动或观点)令人厌倦的，缺乏新鲜感的
    If you say that a place, an activity, or an idea is stale, you mean that it has become boring because it is always the same.

    e.g. Her relationship with Mark has become stale...
           她和马克之间已经没有新鲜感了。
    e.g. The Government, he said, were sticking to stale ideas.
           他说政府仍在抱残守缺。