insidious
C1CEFR level
55/100Rarity: uncommon
FormalRegister
Proceeding gradually and subtly, with harmful effects that are not immediately apparent.
The insidious spread of misinformation eroded trust before anyone noticed.
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 insidious 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.