/dim"owt'/ , n.
1. a reduction or concealment of night lighting in wartime to make the source less visible to an enemy from the air or sea.
2. a reduction of night lighting caused by a failure in an electric generating system or a reduction in its output.
Also, dimout . Cf. blackout (def. 2), brownout .
[ 1940-45; DIM + (BLACK)OUT ]