They're off-limits

• Some kindergarten rules
• Not-to-do list
• They're taboo: Hyph
• They're not allowed
• Forbidden activities
• See 47 Across, e.g.
• Actions to avoid: Hyph
• They're unacceptable
• Cake and ice cream, to dieters

Wiktionary Word definitions in Wiktionary
n. (plural of nono English)