alertyoudaoicibaDictYouDict
alert: [17] Alert comes, via French, from an Italian phrase all’ erta ‘on the look-out’, or literally ‘at the (alla) watch-tower (erta)’. Erta was short for torre erta, literally ‘high tower’, in which the adjective erta ‘high’ came ultimately from Latin ērectus, the past participle of ērigere ‘raise’.
=> erect
watchtower (n.)youdaoicibaDictYouDict
also watch-tower, 1540s, from watch (v.) + tower (n.).