efficacious

Everyday

(formal) Working well; producing the result you want, especially of a medicine or treatment. tree →

In the lessons

A formal exam and medical word. It tells the reader that something truly works. In science: scientists test whether a treatment is efficacious with fair tests. Phrases: «efficacious in», «highly efficacious», «efficacious against».

Examples

• The new medicine proved efficacious against the cough. tree →
• Rest and fluids are efficacious for a cold. tree →
• The scientists tested whether the cream was efficacious. tree →
• A warm bath was efficacious in calming the baby. tree →
• The spray was efficacious against greenfly. tree →
• Practice is the most efficacious way to learn tables. tree →

Note

Formal. Noun: «efficacy». Close words: «effective» (works), «efficient» (works without waste). In speech say «works well», «effective». Pronounced ef-ih-KAY-shus.