# SST vs su

> English confusable word pair

## The two words

### SST
*noun · frequency rank #43,385*
Initialism of supersonic transport.

### su
*noun · frequency rank #8,094*
Alternative form of xu (“former Vietnamese currency”).

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