Meaning

adjective producing or capable of producing an intended result or having a striking effect; -LewisMumford

adjective able to accomplish a purpose; functioning effectively; -G.B.Shaw

adjective works well as a means or remedy

originEtymology tree Proto-Indo-European *h₁éǵʰ Proto-Indo-European *-s Proto-Indo-European *h₁éǵʰs Proto-Italic *eks Latin ex Latin ef- Proto-Indo-European *dʰeh₁k- Proto-Indo-European *-yéti Proto-Indo-European *dʰh₁kyéti Proto-Italic *θakjō Proto-Italic *fakjō Latin faciō Latin efficiō Proto-Indo-European *-wós Proto-Indo-European *-iHwósder. Latin -īvus Latin effectivusbor. French effectifder.…

Etymology from Wiktionary, CC BY-SA 3.0