without lights; unlit
Typically used for vehicles (bicycles, cars) traveling at night without headlights or taillights on. Often appears in traffic safety contexts.
Riding without lights at night is extremely dangerous.
The police are cracking down on bicycles without lights.
Compound of 無 (mu, 'without') + 灯火 (tōka, 'lamp light'). The reading とうか for 灯火 is a standard on'yomi combination.