a container that is heated to a very high temperature, so that substances that are put inside it, such as metal, will melt or burn

People who work with furnaces in a steel factory need to wear protective clothing. 钢厂里在熔炉边工作的人都需要穿防护服。

This room's like a furnace (= is very hot)! 这个房间热得像熔炉！

a piece of equipment for heating a building

It's cold in here - should I turn on the furnace? 这里很冷——要不要我把暖气炉打开？