the.com/decorum
The art of behaving as if grandma is always watching, because socially she is.
means Dignified, proper behavior that fits the occasion, especially in formal or public settings.
from From Latin decorum, the neuter of decorus, meaning fitting or seemly, rooted in decere, to be suitable.
Roman rootsCicero treated it as a core rhetorical virtue.
Theater ruleClassical drama banned onstage violence as undecorous.
Same familyShares ancestry with decorate and decent.