alertness

UK:^*^*UK and possibly other pronunciationsUK and possibly other pronunciations/əˈlɜː^rtnɪs/

a•lert /əˈlɜrt/USA pronunciation adj.

paying complete attention;
wide-awake:The children were alert, following the teacher's instructions.
watchful and ready to act;
vigilant:The prison guard was alert at his post.[~ + to]remained alert to the danger.

a warning or alarm of an impending military attack, a storm, etc.:a tornado alert.
the period in which such a warning or alarm is in effect.

v. [~ + object (+ to + object)]

to warn (troops, ships, etc.) to prepare for a coming attack:alerted the air squadron.
to make aware of;
warn:alerting the townspeople to the danger.

Idioms

Idioms on the alert, prepared for danger or opportunity.

a•lert•ly, adv.
a•lert•ness, n. [uncountable]

a•lert (ə lûrt′),USA pronunciation adj.

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.
on the alert, on guard against danger;
in readiness;
vigilant:The state police are on the alert for an escaped convict believed to be in the area.

v.t.

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.

Latin ērigere to erect
Italian all'erta, equivalent. to all(a) to, on the + erta lookout, watchtower, origin, originally feminine of erto, past participle of ergere
1590–1600; 1940–45 for def. 4;