1. The chamber in a steam locomotive where fuel is burned to heat water and produce steam.
Usage: plural of firebox; chiefly historical or technical
2. A metal box or chamber designed to contain a fire, especially in a furnace or heating system.
Usage: plural of firebox; general use

Examples

• The engineer inspected the fireboxes of the old steam engines before the restoration project began.
• Modern heating systems have replaced traditional fireboxes with more efficient burners.
• The fireman kept the fireboxes hot during the long journey across the mountains.
• Maintenance crews regularly cleaned the fireboxes to remove ash and debris.
• The locomotive's fireboxes were lined with special refractory brick to withstand extreme temperatures.