Obnoxious means extremely annoying or offensive in a way that's hard to ignore. An obnoxious person might talk loudly during a movie, brag constantly about themselves, or make rude comments that upset others. The word describes behavior that goes beyond mildly irritating: it's the kid who won't stop tapping their pencil even after you've asked three times, or the teammate who complains about everything during practice.

What makes something obnoxious is usually the combination of being both bothersome and inconsiderate. A baby crying on an airplane is annoying but not obnoxious, because the baby can't help it. But someone playing music without headphones on the bus is being obnoxious because they're choosing to bother everyone around them.

The word often describes people, but it can describe sounds, smells, or anything else that overwhelms your senses in an unpleasant way. An obnoxious smell might be so strong and awful that you can't think about anything else. An obnoxious color scheme might be so bright and clashing that it hurts to look at.

Most people don't realize when they're being obnoxious, which is part of what makes it so frustrating to deal with.