# FiO2

> English word · Noun

## Definitions
1. Initialism of fraction of inspired oxygen.

## Etymology
Initialism of fraction [of] inspired + O₂ (“oxygen”).
Etymology tree
Middle English fraccioun
English fraction
Proto-Indo-European *h₂epó
Proto-Germanic *ab
Proto-West Germanic *ab
Old English æf
Old English of
Middle English of
English of
English inspired
Proto-Indo-European *h₂eḱ-der.?
Ancient Greek ὀξύς (oxús)
Proto-Indo-European *ǵenh₁-
Proto-Indo-European *-os
Proto-Indo-European *ǵénh₁os
Proto-Hellenic *génos
Ancient Greek γένος (génos)
French oxygènebor.
English oxygen
English FiO2

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/fio2