11th commandment
nounEtymology In reference to the biblical Ten Commandments, carrying the implication that the convention is of very high importance (similar to the Ten Commandments).
1
Idiomatic A well-known convention (often the most well-known of a certain field) which supposedly can not or should not be broken.
- A “hood,” he said, isn’t necessarily a neighborhood, adding that the same culture is seen on Wall Street, “where the 11th commandment is ‘Thou shalt not get caught.’ ”2016 September 29, Cathy Locke, “Philosopher Cornel West calls honesty, integrity ‘countercultural’”, in The Sacramento Bee, archived from the original on 30 Sep 2018:
- Some of the accused did not know Basil’s real identity; the others stuck by the old-school criminal’s 11th commandment, “Thou shalt not grass.”2018 September 8, Duncan Campbell, “After the Hatton Garden heist: 'The actors will profit more than the criminals'”, in The Guardian, archived from the original on 30 Sep 2018: