Thesaurus.com
Dictionary.com

on alert

ADJECTIVE
on call
Synonyms
WEAK
accessible at hand at one's beck and call at one's disposal at one's fingertip available handy night call on deck on-the-spot prepared standing by within reach
ADJECTIVE
vigilant
Synonyms
STRONGEST
anxious attentive aware cautious circumspect keen observant wary
WEAK
acute agog alert guarded looking for looking to on guard on the ball on the job on the lookout on the qui vive on toes open-eyed sharp sleepless unsleeping waiting on wakeful wide-awake with eyes peeled with weather eye open
Antonyms
STRONGEST
careless heedless ignorant inattentive incautious indifferent indiscreet rash thoughtless unaware uncareful unobservant
WEAK
impulsive negligent

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

They are still hurting, still missing the loved ones they lost, and they must surely be forever on alert for similar devastations that could come and upend their lives again.

From Salon ● Sep. 11, 2026

Dog owners have been put on alert after suspected palm oil washed up on a Merseyside beach.

From BBC ● Aug. 21, 2026

The stock-market veteran putting investors on alert is Kevin Muir, author of The MacroTourist newsletter and formerly a derivative trader at RBC Capital Markets and Wintor Capital.

From MarketWatch ● Jul. 2, 2026

The yen weakened against the dollar in early trade, with the market remaining on alert for possible FX intervention.

From The Wall Street Journal ● Jul. 1, 2026

Lately, I felt like I always had to be on alert for the next raccoon invasion.

From "Crenshaw" by Katherine Applegate

Vocabulary.com logo
by dictionary.com

Join 14,000,000 vocabulary learners

Start learning new words today on VocabTrainer.
You'll remember them forever.

Start training