What does uninflammable mean?
Uninflammable means incapable of catching fire or being ignited. It is a precise but relatively uncommon adjective, especially in Britain and the United States, where “nonflammable” is generally more frequent in technical writing, safety instructions, and product descriptions. In ordinary prose, the word often describes materials, fabrics, or constructions that will not ignite under ordinary conditions, though it should not automatically be treated as a synonym for the stronger “fireproof.” The prefix has a potentially misleading history: “inflammable” traditionally means flammable, so “uninflammable” means not flammable. Although this usage is established and understandable, readers encountering it in modern signage may prefer the clearer “nonflammable.” The word remains useful when a writer wants to state plainly that a substance or structure is not combustible. It also illustrates how a familiar negative prefix can transform an adjective whose positive form is less common than its modern synonym.
adjectiveNot flammable; incapable of being set on fire or easily ignited.
- Unable to be set on fire or ignited under ordinary conditions.
"The laboratory was equipped with uninflammable cabinets and storage containers."
"The aircraft was upholstered in uninflammable fabric."
"Even the supposedly uninflammable storage shed was extensively damaged by the blaze."
Its older building blocks can mislead: “inflammable” means flammable, so “uninflammable” means not flammable—though modern safety language usually prefers “nonflammable.”
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does uninflammable come from?
Uninflammable was formed in English by adding the negative prefix un- to inflammable. Inflammable comes from Latin inflammare, “to set on fire,” which was built on flamma, “flame,” and connects the word to inflame, inflammation, and flame. The formation reflects an older English use of inflammable to mean flammable, a usage that can still cause confusion today.
Related word forms
How uninflammable is actually used
Relatively uncommon and more formal; “nonflammable” is generally preferred in contemporary technical writing, safety instructions, and product descriptions. It does not necessarily imply that a material is completely fireproof under extreme conditions.
Easily confused with uninflammable
Inflammable means capable of catching fire, whereas uninflammable means resistant to ignition.