Source : Webster's Revised Unabridged Dictionary (1913)

Smokeless \Smoke"less\, a.
   Making or having no smoke. ``Smokeless towers.'' --Pope.

Source : WordNet®

smokeless
     adj : emitting or containing little or no smoke; "smokeless
           factory stacks"; "smokeless fuel"; "a smokeless
           environment" [ant: {smoky}]