retention curve
C1CEFR level
85/100Rarity: very rare
TechnicalRegister
A plot showing the share of users still active over successive periods after they first engaged.
A retention curve that flattens rather than falling to zero signals a sticky product with a loyal core.
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 retention curve 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.