Qui vive

1.

The challenge of a French sentinel, or patrol; - used like the English challenge: "Who comes there?" To be on the qui vive to be on guard; to be watchful and alert, like a sentinel.

Noun

1.

qui vive - condition of heightened watchfulness or preparation for action; "bombers were put on alert during the crisis" Synonyms: alert

air alert, alert, preparation, preparedness, readiness, red alert, strip alert