Dictionary:

brownout

  (broun'out')

A reduction or cutback in electric power, especially as a result of a shortage, a mechanical failure, or overuse by consumers.

[BROWN + (BLACK)OUT.]

A lowering of AC power voltage for some period of time. Brownouts can be very harmful to electronic equipment if sustained for long periods. Brownouts can cause flickering or a dimming on screen, and the computer may experience intermittent problems as a result. See blackout.

1. To complete the application of a base-coat plaster.
2. The setting of base-coat plaster, which darkens, or browns, as it sets.
3. The dimming of lights as a consequence of a reduction of voltage furnished to a section of a city (or an entire city) by the electrical utility.

The noun has one meaning:

Meaning #1: darkness resulting from the extinction of lights (as in a city invisible to enemy aircraft)
  Synonyms: blackout, dimout