1 [with object] openly resist or refuse to obey:a woman who defies convention be of such a kind or nature that (a specified attitude or action) is almost impossible:his actions defy belief the outfit defied adequate description
2 [with object and infinitive] appear to be challenging (someone) to do or prove something:he glowered at her, defying her to mock him archaic challenge (someone) to fight: go now, defy him to the combat