early 14c., from O.Fr. alarme, from It. all'arme "to arms!" (lit. "to the arms"). An interjection that came to be used as the word for the call or warning (cf. alert). Extended 16c. to "any sound to warn of danger or to arouse." Weakened sense of "apprehension, unease" is from 1833. Variant alarum is due to the rolling -r- in the vocalized form. Sometimes in early years Anglicized as all-arm. The verb is 1580s, from the noun.