1. not capable of catching fire and burning; fireproof

Examples

• The building was constructed with incombustible materials like steel and concrete.
• Asbestos was once popular as an incombustible insulation material.
• The safe was made of incombustible metal to protect important documents.
• Fire codes require incombustible barriers between certain areas.
• The theater’s curtains were treated with chemicals to make them incombustible.
• Stone and brick are naturally incombustible building materials.