# femtobarn

> English word · Noun

## Definitions
1. A unit of area equal to a billionth of a millionth (10⁻¹⁵) of a barn

## Etymology
From femto- + barn.

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