on the alert

1. Watchful, fully prepared, as in The inspectors are always on the alert for a manufacturing error. [Late 1700s]

Example Sentences

It’s a play on the alert that heralded a new participant in online chat rooms of the 1990s and aughts, a time when many of this phrase’s current users weren’t born.

Read more on The Wall Street Journal

Motorists have been warned to be on the alert for scammers posing as car finance lenders offering fake compensation.

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In practice, this could include ballistic missiles fired at RAF Akrotiri but here in Britain the Security Service, MI5, will also be on the alert for any hostile acts by Iran that could include sabotage and arson carried out by criminal gangs.

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It’s a cautious optimism, though, competing with the anxiety Dom and Cole generally feel as gay men on the alert for everyday microaggressions, also as tourists who don’t know the language and urbanites not exactly comfortable navigating another country’s backwaters at night.

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Norway and its Nato allies are also on the alert for Russian spy submarines and other vessels in the Arctic.

Read more on BBC