off-limits

1. ADJ If a place is off limits to someone, they are not allowed to go there. 禁止入内的

Certain areas have been declared off limits to servicemen. 已经宣布一些地区军人不得出入。

2. ADJ If you say that an activity or a substance is off limits for someone, you mean that they are not allowed to do it or have it. 禁止使用或拥有的[v-link ADJ]

Fraternizing with the customers is off limits. 禁止与顾客过从甚密。