a container is heated to a high temperature, substances such as metal will melt or burn inside it
People who work with furnaces in a steel factory need to wear protective clothing.
This room's like a furnace.
The blacksmith used a hot furnace to shape the molten metal into a sword.
A malfunctioning furnace can pose a risk of carbon monoxide leaks.
In winter, a reliable furnace is essential for maintaining a warm home.
The factory's blast furnace operated day and night to produce steel.
