# A4 vs APL

> English confusable word pair

## The two words

### A4
*name · frequency rank #18,471*
A4 class, a class of steam locomotive used on the London and North Eastern Railway.

### APL
*noun · frequency rank #48,593*
Initialism of acute promyelocytic leukemia.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-09-03.
Canonical page: https://plainspell.com/en/vs/a4-vs-apl