efficacious
C1CEFR level
58/100Rarity: uncommon
FormalRegister
Effective in producing the intended result.
The trial confirmed that the new drug was highly efficacious.
Rarity runs from 0 (a word everyone knows) to 100 (almost never seen outside specialist or literary writing). Level is the word's real difficulty on the CEFR scale, from A1 to C2.
Get words like efficacious on your lock screen, a few a day, with review that makes them stick.
Download on the App Store Lexfall puts a new word on your home and lock screen through widgets, so you learn without opening an app. Free to download. After a free trial, a subscription unlocks every field. Built for iPhone, iOS 15.1 or later.
On a computer?Scan with your iPhone camera.