Meaning of the word "under no circumstances" in English

What does "under no circumstances" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

under no circumstances

US /ˈʌndər noʊ ˈsɜːrkəmstænsɪz/
UK /ˈʌndə nəʊ ˈsɜːkəmstənsɪz/

Phrase

never; absolutely not

Example:
Under no circumstances should you open that door.
I will under no circumstances tolerate such behavior.