dim-out

or dim·out

[dim-out]

noun

a reduction or concealment of night lighting in wartime to make the source less visible to an enemy from the air or sea.
a reduction of night lighting caused by a failure in an electric generating system or a reduction in its output.

Compare blackout(def 2), brownout.

Origin of dim-out

First recorded in 1940–45; dim + (black)out

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for dim-out

Historical Examples of dim-out

Along the shore no lights were showing for the dim-out was rigidly enforced at Sunset Beach.
Voice from the Cave
Mildred A. Wirt