flammable or inflammable? Although flammable and inflammable may appear to be opposites, in fact they have the same meaning. SBut s ince inflammable may seem to mean ‘not flammable’ (from the prefix in- meaning ‘not’ + flammable) and because of the risk of fire and danger to life, use of the word flammable is increasingly preferred, especially in technical contexts: highly flammable solvents. The preferred negative is non-flammable: non-flammable clothing