alarm

Alarm comes from Middle English alarme or alarom, borrowed from Middle French alarme, which came from Old Italian all'arme! — literally 'to arms!, to the weapons!' — ultimately rooted in Latin arma, meaning 'arms, weapons.'

The word began as an actual battle cry telling soldiers to grab their weapons, and over time it settled into English as a general word for any signal of danger.

It shares its root with 'arms,' both tracing back to Latin arma — one word stayed literal, the other became a cry of warning.