A*lert" (ȧ*lẽrt"), a. [F.
alerte, earlier à l'erte on the watch, fr. It. all'
erta on the watch, prop. (standing) on a height, where one can look
around; erta a declivity, steep, erto steep, p. p. of
ergere, erigere, to erect, raise, L. erigere. See
Erect.] 1. Watchful; vigilant; active in
vigilance.
2. Brisk; nimble; moving with celerity.
An alert young fellow.
Addison.
Syn. -- Active; agile; lively; quick; prompt.
A*lert", n. (Mil.) An alarm from
a real or threatened attack; a sudden attack; also, a bugle sound to give
warning. "We have had an alert." Farrow.
On the alert, on the lookout or watch against
attack or danger; ready to act.