What's "defy" mean?

Native speaker’s answer
Rebecca
To "defy" someone means to openly resist or refuse to obey someone. In this video, you can see that Patrick is running around rejecting all signs of Valentine's Day, including unzipping someone's heart costume. You can consider these to be acts of defiance. Ex: I defied my parents when I dropped out of school to join a band. Ex: The citizens defied their corrupt government by striking and holding mass protests.