tonight不属于动词，tonight可以作名词和副词使用。

tonight作名词时意思是:

今晚;今夜;作副词时，意思是: 在今晚;在今夜;

例句: Don't let on to Doris that we are going to the movies tonight, we don't want her to know.我们今晚去看电影的事别告诉桃丽丝,我们不想让她知道。