flammable, inflammable, non-flammable, non-inflammable

Use flammable to mean “capable of catching fire” and non-flammable as its opposite.

• Flammable fabrics have been banned for use in children’s nightwear.
• Christmas trees should be decorated with non-flammable materials.

For the sake of clarity, avoid inflammable (and its opposite, non-inflammable).

• Inflammable is actually a synonym for flammable. However, the prefix in-may be interpreted as a negative and thus lead people to believe mistakenly that a product is safe from catching fire when it is not.