From Longman Dictionary of Contemporary Englishdarkroomdark‧room /ˈdɑːkruːm, -rʊm $ ˈdɑːrk-/ noun [countable] TCPa special room with only red light or no light, where film from a camera is made into photographs
Examples from the Corpus
darkroom• Spitzer produces his drawings in a darkroom by applying a titanium mixture on to parchment, which gradually turns black in daylight.• He took it into a small booth under the stairs which evidently served him as darkroom.• He had had his own darkroom, and had always been taking pictures.• What do you like best about the darkroom?• There was no light on in the room directly above, but amber glowed from the darkroom doorway.• He joined assistants in the darkroom to select from endless photos.• He stood in the darkroom with another trainee, Dale Fitzke, a cripple.• Now she was here and it was just like old times: in the darkroom with Maggie, working on filthy pictures. 