Turning off the lights; putting out illumination (often done at bedtime or to save electricity).
病院では午後10時に消灯の案内が流れた。
In the hospital, an announcement was made at 10 p.m. to turn off the lights.
地震のため一時的に全館が消灯した。
Due to an earthquake, the entire building was temporarily plunged into darkness.
節電のため、オフィスは午後7時に消灯することになっている。
To save electricity, the office is scheduled to turn off the lights at 7 p.m.