noun
vigil
VIJ-il/ˈvɪdʒɪl/
A period of staying awake to keep watch or mark an important occasion.
The group keeps a candlelit vigil beside the memorial flowers through the night.

Etymology
Latin vigilia meant a watch or watchfulness. In English, vigil first referred to devotional watching through the night before a religious festival, then broadened to an occasion of staying awake for a purpose.
In context
i'm keeping an all night vigil so that she doesn't squash any of these guys
More examples
- Neighbors hold a candlelight vigil to remember the victims.
- He maintains a lonely vigil while the rescue team searches.
- Protesters organize overnight vigils outside the courthouse.
Forms
vigil · vigils
vigilance noun — Sustained attention to possible danger or trouble.