Entries linking to alertness
"on the watch," 1610s, from French alerte "vigilant" (17c.), from prepositional phrase à l'erte "on the watch," from Italian all'erta "to the height." Second element from erta "lookout, high tower," noun use of fem. of erto, past participle of ergere "raise up," from Latin erigere "raise" (see erect (adj.)).
The adjective is attested from 1712; the noun is from 1796 as "attitude of vigilance" (as in on the alert); 1803 as "a warning report." The verb is by 1864. Related: Alerted; alerting.
word-forming element denoting action, quality, or state, attached to an adjective or past participle to form an abstract noun, from Old English -nes(s), from Proto-Germanic *in-assu- (cognates: Old Saxon -nissi, Middle Dutch -nisse, Dutch -nis, Old High German -nissa, German -nis, Gothic -inassus), from *-in-, originally belonging to the noun stem, + *-assu-, abstract noun suffix, probably from the same root as Latin -tudo (see -tude).