# set one's hair on fire

> English word · Verb

## Definitions
1. To become wildly impassioned; to behave crazily.

## Etymology
Possibly from stories of Viking marauders said to have set their hair and beards on fire when running into battle in order to appear fanatical and fearsome.

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