watchful; awareactive; briskalertly advalertness noun[French alerte from Italian all’ erta, literally ‘on the lookout’]
an alarm or other signal that warns of danger, e.g. from hostile aircraftthe danger period during which an alert is in effecton the alert on the lookout, esp for danger or opportunity
to call (somebody) to a state of readiness; to warn (somebody)(often + to) to cause (somebody) to be aware, e.g. of a need or responsibility