Source : Webster's Revised Unabridged Dictionary (1913)

Godless \God"less\, a.
   Having, or acknowledging, no God; without reverence for God;
   impious; wicked. -- {God"less*ly}, adv. -- {God"less*ness},
   n.

Source : WordNet®

godless
     adj : not revering god [syn: {irreverent}]