# Mach number

> English word · Noun

## Definitions
1. The ratio of the speed of a body to that of sound in the surrounding medium.

## Etymology
After physicist Ernst Mach.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-09-03.
Canonical page: https://plainspell.com/en/word/mach-number