Back in the day, coal miners started calling lanterns with an enclosed flame “safety lamps.” Open flames in coal mines were a big problem, regularly causing deadly explosions. Attempts to help mitigate explosion risks stretch all the way back to the 1700s.
One of the more successful early types of safety lamps is the Davy lamp, invented by Humphry Davy in the early 19th century. In these lamps, the open flame is surrounded by mesh material that can, at least temporarily, prevent the flame from extending too far or getting hot enough to ignite flammable gases in the surrounding atmosphere.
Nowadays we would call these Ex luminaires for mining operations, but the term ‘safety lamp’ is still quite common and widely understood in the mining industry and other hazardous areas.