English
inefficacious
From in- + efficacious.
A compound of in- + efficacious
Proto-Indo-European *dʰeh₁k-
…
Latin faciō ‘to make, construct, fashion, frame, build, erect’
Latin efficiō ‘to make out, work out’
Latin efficāx
Old French efficacieux
English efficacious
Today it means
adj Incapable of having the intended consequence.
Language periods are conventional ranges, not dates for this word.
Etymograph / inefficacious