# ECM vs ef

> English confusable word pair

## The two words

### ECM
*noun · frequency rank #33,219*
Initialism of engine control module.

### ef
*noun · IPA /ˈɛf/ · frequency rank #20,103*
The name of the Latin script letter F/f.

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