What is On the alert?
On the alert definition and meaning on Dictionary terms:
fully aware and attentive; wide-awake; keen: an alert mind.
swift; agile; nimble.
an attitude of vigilance, readiness, or caution, as before an expected attack.
a warning or alarm of an impending military attack, a storm, etc.: We’d just boarded the bus when the alert sounded.
the period during which such a warning or alarm is in effect.
verb (used with object)
to warn (troops, ships, etc.) to prepare for action.
to warn of an impending raid, attack, storm, etc.: The radio alerted coastal residents to prepare for the hurricane.
to advise or warn; cause to be on guard: to alert gardeners to the dangers of some pesticides.