unspoken rule
nounUK /ʌnˈspəʊkən ruːl/
US /ʌnˈspoʊkən ruːl/
A rule that everyone knows but nobody says out loud.
It's an unspoken rule that you don't take the last cookie without asking.
RELATED WORDS
OTHER MEANINGS
2. A social habit that a group follows without ever writing it down.
In their family, it was an unspoken rule to call grandma every Sunday.
3. An expected way to behave that people learn by watching others.
New students quickly pick up the unspoken rule of staying quiet in the library.
4. A hidden agreement between friends that keeps things fair.
Sharing snacks became an unspoken rule among the teammates.