Cake and ice cream, to dieters

• Misdeeds, to the law
• Forbidden acts: Hyph
• Taboos for toddlers
• Taboos (and title of this puzzle)
• Forbidden behaviors: Hyph
• Running with scissors and others
• Forbidden activities
• Faux pas
• Don'ts

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