Meaning

noun fear resulting from the awareness of danger

noun a device that signals the occurrence of some undesirable event

noun an automatic signal (usually a sound) warning of danger

originFrom Middle English alarme, alarom, borrowed from Middle French alarme, itself from Old Italian all'arme! (“to arms!, to the weapons!”), ultimately from Latin arma (“arms, weapons”).

Etymology from Wiktionary, CC BY-SA 3.0