# FEI vs fermi

> English confusable word pair

## The two words

### FEI
*name · frequency rank #22,967*
Initialism of Federal Executive Institute.

### fermi
*noun · IPA /ˈfɜː(ɹ)mi/ · frequency rank #35,718*
An obsolete name of the unit of length equal to one femtometre (10⁻¹⁵ m).

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/vs/fei-vs-fermi