# femtometre

> English word · Noun

## Definitions
1. An SI unit of length equal to 10⁻¹⁵ metres. Symbol: fm

## Etymology
From femto- + metre.

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