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be on alert

VERB
watch
Synonyms
STRONGEST
attend guard protect take care of wait
STRONG
mind oversee patrol police superintend tend watch over
WEAK
be on the lookout be vigilant be wary be watchful care for keep an eye on keep eyes open keep eyes peeled keep watch over look after look out pick up on ride shotgun for take heed
Antonyms
STRONGEST
ignore neglect
WEAK
harm hurt overlook pass by

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.

German forecasters said parts of the country needed to be on alert for thunderstorms, hail and heavy rain over the weekend.

From Barron's • Jun. 19, 2026

Gardeners and growers across the northern half of the UK will then need to be on alert on Saturday night as a frost is possible.

From BBC • May 9, 2026

The IMF chief said regulators should be on alert for any signs of instability in the financial system as a consequence of the conflict.

From The Wall Street Journal • Apr. 9, 2026

Anyone playing in the already-volatile small-cap arena should be on alert to avoid getting burned.

From Barron's • Nov. 18, 2025

Whether or not a human knew what they were, an instinct inside them knew to be on alert, to be just a little afraid.

From "Night Owls" by A.R. Vishny

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