noun
without lights; unlit
Typically used for vehicles (bicycles, cars) traveling at night without headlights or taillights on. Often appears in traffic safety contexts.
夜間の無灯火走行は非常に危険です。
Riding without lights at night is extremely dangerous.
警察は無灯火の自転車を取り締まっている。
The police are cracking down on bicycles without lights.
消灯 means 'turning off lights', often used for scheduled lights-out, not the illegal absence of required 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.