off–lim·its 
/ˈɑ:fˈlɪməts/ adjective
not used before a noun /ˈɑ:fˈlɪməts/ adjective 1 — used to say that people are not allowed to enter a place or use something ▪ The basement and garage will be off-limits during the renovations. ▪ The historical documents have been placed off-limits. — often + to ▪ Certain areas in the museum are currently off-limits to visitors. 2 — used to say that people are not allowed to talk about something ▪ The subject of sex was off-limits in her family.
