the world > matter > light > darkness or absence of light > dimness or absence of brightness > make dim [verb (transitive)] > reduce the brightness of (2)
transitive. To lower the output of (a lamp, gas) by turning a handle, tap, etc.; to lower the temperature of (an electrical appliance, heating…
to dim out: to reduce the brightness of (street-lighting, etc.), esp. in time of war; to impose a ‘dim-out’ on (a city, etc.).