Defy

To renounce or dissolve all bonds of affiance, faith, or obligation with; to reject, refuse, or renounce.

To provoke to combat or strife; to call out to combat; to challenge; to dare; to brave; to set at defiance; to treat with contempt; as, to defy an enemy; to defy the power of a magistrate; to defy the arguments of an opponent; to defy public opinion.

A challenge.