ˈgāgənˌshīn noun
( -s )
Usage: often capitalized
Etymology: German, from gegen against, counter- + schein shine
: a faint elliptical nebulous light about 20° across on the ecliptic and opposite the sun best seen during September and October when in the constellations Aquarius and Pisces and probably associated in origin with the zodiacal light — called also counterglow