Since it was borrowed in the year 1400, the word alarm has been spelled alarom, alarum, a larme, al'arme, and allarm until today's spelling became standardized around the turn of the eighteenth century. As a noun, it had a lot of meanings, all of which are somehow related: the "clock" definition comes from the "warning" definition, and that came from the "awareness of danger" definition. That traces to Old French alarme, which had the latter meaning and was borrowed from a contraction of the Italian phrase alle arme, or "to arms". But the plot thickens: alle is also a contraction, of a ("to"; from Latin and possibly Etruscan) and le (an article). Arme is the plural of arma, meaning "weapon". That derives from Latin and eventually hails from Proto-Indo-European hermos, "to fit together". The word alarm peaked in usage in the 1820s and has declined since.
Hello! I'm Adam Aleksic, a sophomore studying linguistics and government at Harvard University, where I founded the Harvard Undergraduate Linguistics Society. I also have disturbing interests in politics, vexillology, geography, board games, conlanging, and law.