Nonflammable means something will not burn easily or support a fire under normal conditions. A nonflammable material like concrete or steel will not ignite like wood or paper would. Fire safety labels on buildings and containers often mark materials as nonflammable to show they are much safer from fire hazards.

This word matters in construction, manufacturing, and everyday safety. Firefighters wear nonflammable gear so their clothing is far less likely to catch fire while they work. Theaters use nonflammable curtains to help protect audiences. Airlines require nonflammable materials in airplane interiors. Scientists and engineers carefully test materials to ensure items like children's pajamas meet nonflammable standards.

Be careful not to confuse nonflammable with inflammable. This trips up many people because inflammable actually means the opposite of what it sounds like: it describes things that catch fire easily, just like flammable. Water is nonflammable. Gasoline is inflammable (or flammable). That’s why safety labels today almost always use flammable and nonflammable to avoid dangerous confusion.