Where does “unefficacious” come from?
unefficacious (English) comes from English efficacious, from Old French efficacieux, from Latin efficāx, from Latin efficiō, from Latin ex, from Latin commūnicō, from Latin commūnis, from Old Latin com(m)oinis — resin.
unefficacious (English): Not efficacious
Ancestry of “unefficacious”, step by step