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.

resist or confront with resistance; "The politician defied public opinion"; "The new material withstands even the greatest wear and tear"; "The bridge held"

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

elude, especially in a baffling way; "This behavior defies explanation"

Drug Education for Youth.