Etymology From French alerte (“alert”), from the phrase à l'erte (“on the watch”), from Italian all'erta (“to the height”), from erta (“lookout, tower”).
I saw an alert young fellow that cocked his hat upon a friend of his who entered just at the same time with myself1712 June 22 (Gregorian calendar), [Joseph Addison; Richard Steele et al.], “WEDNESDAY, June 12, 1712”, in The Spectator, number 408; republished in Alexander Chalmers, editor, The Spectator; a New Edition, […], volume V, New York, N.Y.: D[aniel] Appleton & Company, 1853, →OCLC:
Etymology From French alerte (“alert”), from the phrase à l'erte (“on the watch”), from Italian all'erta (“to the height”), from erta (“lookout, tower”).
1
An alarm.
2
A notification of higher importance than an advisory.