Dic: off limits (to or for)

1. ADJ : usu v-link ADJ, oft ADJ to n

If a place is off limits to someone, they are not allowed to go there.

• Downing Street has been off limits to the general public since 1982.
• Certain areas have been declared off limits to servicemen.

2. ADJ : v-link ADJ, oft ADJ for n

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.

• Fraternizing with the customers is off-limits.

..... Cobuild

Cf. out-of-bounds

1. [Lit.] outside the boundaries of the playing area. (*Typically: be ~; get ~; go ~.)

• The ball went out-of-bounds just at the end of the game.
• The whistle blew when Juan went out-of-bounds.

2. and *off-limits [Fig.] forbidden. (*Typically: be ~.)

• This area is off-limits. You can't go in there.
• Don't go there. It's out-of-bounds.
• That kind of behavior is off-limits. Stop it!

.... http://idioms.thefreedictionary.com/off-limits