# UFO vs upon

> English confusable word pair

## The two words

### UFO
*noun · IPA /ˌjuːɛfˈəʊ/ · frequency rank #15,539*
Initialism of unidentified flying object; (loosely) an alien spacecraft.

### upon
*preposition · IPA /əˈpɒn/ · frequency rank #798*
A higher-register or more formal alternative to on in most, though not all, prepositional uses.

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