Definitions
01watchful
B1 · Intermediate
adj. watching and listening carefully so that you notice things quickly.
adj. fully aware and attentive; wide awake and ready to act or respond.
“The security guard stayed alert throughout the night to keep the building safe.”
“Despite the long hours of the flight, the pilot remained alert and responded immediately to the slight change in engine vibration.”
Antonyms
02to warn
B2 · Upper Intermediate
v. to tell someone about a danger or a problem so they can be ready.
v. to notify someone of a potential danger, problem, or important event.
“A neighbor called to alert us that our garage door was still open.”
“The intelligence agency acted quickly to alert the local authorities about the credible threat to the public event.”
03a warning
B1 · Intermediate Countable noun
n. a message or signal that warns people of danger.
n. a signal, such as a siren or digital notification, that warns of an immediate danger or important condition.
日本語:警報※
Español:alerta
“The phone sent out a loud alert to warn everyone about the coming storm.”
“The system triggered an automatic alert when the server temperature exceeded the safe operating limit.”
Synonyms
04readiness
B2 · Upper Intermediate Uncountable noun Military
n. a state of being ready for a sudden attack or danger.
n. a condition of heightened watchfulness or preparation for action, especially in a military or emergency context.
“The army was on high alert after the peace talks failed.”
“The coastal defenses were placed on full alert following reports of unidentified vessels entering territorial waters.”
Collocations
Common phrases and expressions where native English speakers use the word “alert” in context.
Verb
01. keep someone alert
“The cold air helped keep the driver alert during the long night journey.”
verb + noun + adj
02. remain alert
“Security guards must remain alert throughout their entire shift to ensure the building's safety.”
verb + adj
Adjective
03. alert to
“Investors need to be alert to sudden changes in the global market.”
adj + prep
04. highly alert
“The soldiers were highly alert as they moved through the dense jungle.”
adv + adj
Preposition
05. on full alert
“The emergency services were placed on full alert following the hurricane warning.”
prep + noun
06. on the alert
“Police are on the alert for any suspicious activity near the stadium.”
prep + noun
Real-World Examples
“The 2-mile-long fire front, with flames up to 30 metres (98ft) high, was brought under control later in the day, the regional civil protection chief said, though crews remained on alert for flare-ups.” “The flight crew’s timeline of the event was set out by the NTSB, detailing how they experienced a “high vibration” engine alert during the flight climb.” “Local authorities issued a level five emergency warning, its highest alert, on Thursday.” “They got a dog to stay outside to alert them of any trespassers.” 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”).
Formed within English by conversion, from alert (adjective). Compare French alerter.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.
Word family
NOUN
ADJECTIVE
Domains
- Exam level
- CambridgeCambridgeCambridge English QualificationsThe exam suite from Cambridge University Press & Assessment, from A1 Movers up to C2 Proficiency. The benchmark names double as CEFR labels.C1 AdvancedIELTSIELTSInternational English Language Testing SystemThe 0–9 band test co-owned by the British Council, IDP, and Cambridge. Used for university entry, work, and migration.7.0–8.0TOEFL iBTTOEFL iBTTest of English as a Foreign Language, Internet-Based TestETS's academic English test, the standard route for US university admissions. Scored 0–120, with a 1–6 scale since 2026.1–6 scale: 5.0–5.595–113TOEICTOEICTest of English for International CommunicationETS's workplace English test, big in Japan and Korea. Listening & Reading scores 10–990 and tops out at C1.945–990
- Frequency
- Common
- Level
- C1 · AdvancedOxford
- Updated
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QR code
englishreference.com/q/alert
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「日本語」「カタカナ語」 data: JMdict (EDRDG), CC BY-SA 4.0
Traducciones: Kaikki.org (Wiktionary), CC BY-SA 4.0