You can say this if you think a situation, or someone's behaviour, isn't good enough or isn't acceptable.
- "You've failed another exam, and it simply won't do. You've got to try harder."
- "Being seen with that boy just won't do, David. He's not like us."
"But he's my best friend, Mum. And I'm learning all this stuff about Africa."
This is typically used in British English but may be used in other varieties of English too.
Her teacher said, "This just won't do, Anna." He was saying that
Contributor: Matt Errey