from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. darkness resulting from the extinction of lights (as in a city invisible to enemy aircraft)
Sorry, no etymologies found.
During World War II, the United States was adhering to a wartime "dimout" and in 1942 and 1943, there was no ball drop.
During those war years, New York was subject to a "dimout" of lights intended to protect the city from Axis bombings.
Tradition took root and the ball has heralded a new beginning almost every year since - in 1942 and 1943, during World War II, the ball was temporarily put out of commission by a war-time "dimout."