qui vive

/ˈki ˌviv/

When you're on the qui vive, you're especially vigilant, carefully keeping watch. Your dog might believe it's her responsibility to be on the qui vive all day, barking at every little noise she hears.

You'll almost always find this term in the phrase "on the qui vive." It comes from the question French guards and sentries would commonly ask visitors to a castle or fort: "Qui voulez-vous qui vive?" Literally, this means "Whom do you wish to live?" — in other words, "Whose side are you on?" Today, being on the qui vive means that you're on the alert, like a sentry, watchman, or guard dog.

Definitions of qui vive

1. noun

   condition of heightened watchfulness or preparation for action
   synonyms: alert

   types:

   air alert

   the condition in which combat aircraft are airborne and ready for an operation

   red alert

   the highest level of alert when an attack by the enemy seems imminent (or more generally a state of alert resulting from imminent danger)

   strip alert

   a state of readiness for domestic defense aircraft

   type of:

   preparation, preparedness, readiness

   the state of having been made ready or prepared for use or action (especially military action)