Meaning of ALERT in English

ALERT

I. ə-ˈlərt adjective

Etymology: Italian all'erta, on the watch, literally, on the height

Date: 1618

1.

a. : watchful and prompt to meet danger or emergency

b. : quick to perceive and act

2. : active , brisk

Synonyms: see watchful , intelligent

• alert·ly adverb

• alert·ness noun

II. noun

Date: 1803

1. : a state of careful watching and readiness especially for danger or opportunity

on 24-hour alert

2.

a. : an alarm or other signal of danger

b. : an urgent notice

an alert to parents…about new immunization requirements — Ann Schrader

3. : the period during which an alert is in effect

III. transitive verb

Date: circa 1868

1. : to call to a state of readiness : warn

2. : to make aware of

alert ed the public to the dangers of pesticides

Merriam-Webster's Collegiate English vocabulary.      Энциклопедический словарь английского языка Merriam Webster.