# STI vs stiff

> English confusable word pair

## The two words

### STI
*noun · frequency rank #26,266*
Initialism of sexually transmitted infection (also S.T.I.).

### stiff
*adjective · IPA /stɪf/ · frequency rank #8,357*
Rigid; hard to bend; inflexible.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-09-03.
Canonical page: https://plainspell.com/en/vs/sti-vs-stiff