English vocabulary · C2
Efficacious
/ˌɛf.ɪˈkeɪ.ʃəs/ · adj.
It means something that works and produces the result you wanted.
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Example sentences
- The new drug proved efficacious within hours.
- Her efficacious advice solved the problem fast.
Word origin and roots
from Latin
- ef — out (from Latin)
- fic — make (from Latin)
Synonyms and nuances
- EFFECTIVE — works as planned (General & Common)
- POTENT — having great force (Strong & Powerful)
- SUCCESSFUL — achieving the goal (Outcome-Focused)
Words with the same root
fic — make
- perfect — made completely right
- infect — make sick by spreading germs
- defect — a flaw made by accident
Lesson notes
Efficacious. It means something that works and produces the result you wanted.
Similar words are effective, potent, and successful. Use efficacious when a treatment or method clearly produces the result you wanted.
The new drug proved efficacious within hours. Her efficacious advice solved the problem fast.
From Latin. Ef- means out. Fic- means make. Making a real result come out — that is efficacious.