1) Gegenschein 2) Light 3) Visible light 4) Visible radiation 1) Gegenschein 
• (n.) An exceedingly faint roundish or somewhat oblong nebulous light near the ecliptic and opposite the sun, best seen during September and October, when in the constellations Sagittarius and Pisces. Its cause is not yet understood. Called also Gegenschein.
The English name for the skyglow opposite the Sun, very difficult to observe, caused by very thinly spread interplanetary material. Usually known by its German name, the Gegenschein.
Coun'ter·glow` noun (Astron.) An exceedingly faint roundish or somewhat oblong nebulous light near the ecliptic and opposite the sun, best seen during September and October, when in the constellations Sagittarius and Pisces. Its cause is not yet understood. Called also Gegenschein . 
[n] - a faint spot of light in the night sky that appears directly opposite the position of the sun
gegenschein noun a faint spot of light in the night sky that appears directly opposite the position of the sun; a reflection of sunlight by micrometeoric material in space
gegenschein.