The meaning of RED-LIGHT is relating to or being an area with many brothels or sex workers. How to use red-light in a sentence. RED- LIGHT DISTRICT definition: 1. a part of a city where people and businesses sell sex 2. a part of a city where people and…. Learn more. The idiom " red - light district " originated in the late 19th century, primarily in reference to the districts in major cities where brothels and other adult entertainment establishments were concentrated. Meerganj in Allahabad, Uttar Pradesh, is another prominent red - light area in India. The district administration, in collaboration with non-governmental organizations, has undertaken initiatives to support the welfare and rehabilitation of sex workers and their children.