英和和英

to withdraw a warning

an indication or sign suggesting cautiousness

to warn

relax one's vigilance

a warning-signal

a warning to be ready for danger

an early warning

to go at regular intervals round an area to see that there is no trouble

a state of emergency about which a warning needs to be issued

Forewarned is forearmed.

to develop alarming symptoms

You can't be too vigilant.

a loud warning signal produced by a burglar alarm

the state there being heavy security

We need to stay alert.

to be cautious of one's surroundings

We must guard against accidents―take precautions against accidents.

an early‐warning radar

the condition of there being heavy security

an early warning device called {sentry alarm}

a warning sign

to guard with strict vigilance

There are signs of the epidemic spreading, and the Metropolitan Police are on their guard against it.

an early‐warning system

a whistle that is used to signal a warning