in no circumstances
Never; in no case or situation; irrespective of events or conditions. In no circumstances are you allowed to drive home after you've had more than one drink! I'm sorry for my sudden resignation, but in no circumstances will I work for some sexist manager like him.
under no circumstances
At no time; never. Under no circumstances will I allow you to go to a party on a school night.
under no circumstances
and not under any circumstancesFig. absolutely never. Andy: Under no circumstances will I ever go back there again! Rachel: Why? What happened? Sue: Can I talk you into serving as a referee again? Mary: Heavens, no! Not under any circumstances!
in/under no circumstances
used to emphasize that something should never happen or be allowed: Under no circumstances should you lend Paul any money.Don’t open the door to strangers in any circumstances. under no circumstances
In no case; never.