Source : Webster's Revised Unabridged Dictionary (1913)

Inefficaciously \In*ef`fi*ca"cious*ly\, adv.
   without efficacy or effect.

Source : WordNet®

inefficaciously
     adv : in an ineffective manner; "he dealt with the problem rather
           ineffectively" [syn: {ineffectively}] [ant: {efficaciously},
            {efficaciously}]