# exa-

> English word · Prefix

## Definitions
1. In the International System of Units and other metric systems of units, multiplying the unit to which it is attached by 10¹⁸ (a short scale quintillion or long scale trillion).

## Etymology
From Ancient Greek ἕξ (héx, “six”), for the sixth order of 10³, analogous to tera-.

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