英和和英

to warn

an indication or sign suggesting cautiousness

relax one's vigilance

to withdraw a warning

an early warning

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

a warning-signal

a warning to be ready for danger

We need to stay alert.

Forewarned is forearmed.

You can't be too vigilant.

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

We must guard against accidents―take precautions against accidents.

a loud warning signal produced by a burglar alarm

to develop alarming symptoms

the state there being heavy security

to guard with strict vigilance

to be cautious of one's surroundings

an early‐warning radar

the condition of there being heavy security

a whistle that is used to signal a warning

an early warning device called {sentry alarm}

an early‐warning system