Characteristic of being easily ignited and capable of burning rapidly; flammable.

Historically, flammable and inflammable meant the same thing; however, the presence of the prefix in- has misled many people into assuming that inflammable means "not flammable" or "noncombustible".

The prefix in inflammable is not, however, the Latin negative prefix in-, which is related to the English un- and appears in such words as "indecent" and "inglorious".

Instead, this in- is an intensive prefix derived from the Latin preposition in and it also appears in the word enflame, but many people are not aware of this derivation, and for clarity's sake it is advisable to use only "flammable" to give any kind of warnings about burning or catching on fire.