nox

Short definition from Wiktionary

Noun

1. 1
   The period of darkness in each twenty-four hours; a night.
2. 2
   millilux (unit of illuminance)
3. 3
   Alternative form of NOx (nitrogen oxides)
4. 4
   Abbreviation of nitrous oxide.
5. 5
   Any of the various nitrogen oxides produced during combustion.
6. 6
   Alternative form of nox.

Proper noun

1. 1
   The Roman goddess of night.