Effrontery is shameless, bold rudeness that shows no respect for normal social boundaries. It's the kind of audacity that makes people gasp or shake their heads in disbelief. When someone acts with effrontery, they deliberately ignore what's appropriate and don't seem to care who notices.

Imagine a student who gets caught copying homework, and instead of apologizing, demands to know why the teacher is “making such a big deal about it.” That's effrontery. Or picture someone cutting in front of a long line at the water fountain, then acting annoyed when others complain. Effrontery combines both the rude action and the shameless attitude that comes with it.

It's stronger than simple rudeness or impoliteness. Effrontery suggests a kind of brazen confidence that crosses clear lines, the kind that makes observers wonder, “How can they possibly think that's okay?” When you encounter real effrontery, you'll know it: it's that moment when someone's behavior is so outrageously inappropriate that you're left almost speechless.