vigil

noun

1. An instance of keeping awake during normal sleeping hours, especially to keep watch or pray.

2. A period of observation or surveillance at any hour.

   “His dog kept vigil outside the hospital for eight days while he was recovering from an accident.”

3. The eve of a religious festival in which staying awake is part of the ritual devotions.

4. A quiet demonstration in support of a cause.

   “The protesters kept vigil outside the conference centre in which the party congress was being held.”

5. A purposeful surveillance to guard or observe

   Similar: watch