Definition of know better
1
: to be smart or sensible enough not to do something
- You walked home alone? Don't you know better (than that)?
- She'll know better than to trust them again.
- There's no excuse for his behavior. He's old enough to know better.
- Don't blame him. He's just a child and he doesn't know (any) better.
2
: to know or understand the truth about something
- She tried to tell me that it wasn't her fault, but I know better.
3
: to know or understand more than other people
- You can't tell him what to do. He always thinks that he knows better.
