# FIO

> English word · Noun · frequency rank #81,328

## Definitions
1. Initialism of field interrogation and observation.
2. Initialism of fraction of inspired oxygen.

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