Flammable and inflammable both mean the same thing: something can catch fire easily. This surprises many readers because in often means “not” in English, as in incorrect or invisible. But that is not what is happening here.
In inflammable, the in comes from Latin and is related to the idea of setting something on fire. So inflammable does not mean “not flammable.” It means combustible, just like flammable.
Examples:
- Flammable gas means the gas can ignite easily.
- Inflammable liquid means the liquid can ignite easily too.
Because the word inflammable can be misunderstood, many safety organizations and labels prefer flammable. It is clearer at a glance and reduces the chance that someone will read it as the opposite meaning.
So if you see either word on a label, treat it as a warning: keep the substance away from heat, sparks, and open flames.
