An Etymological Dictionary of Astronomy and Astrophysics

1. A period of darkness caused by a complete loss of electrical power in a particular area.
   

2. The extinguishing of all artificial light enforced as a precaution against air raids.

Etymology (EN): → black; → out.

Etymology (PE): Xâmušzâr, târikzâr from xâmuš “extinguished,” → extinction, târik, → dark,

• -zâr suffix denoting profusion and abundance, sometimes with negative nuance, such as in šurezâr “unfertile, salty ground; nitrous earth,” xoškzâr “arid land far from water,” lajanzâr “field of black mud, marsh,” kârzâr “a field of battle; conflict; engagement.”