English Reference

Word

flammable

US/ˈfɫæməbəɫ/

UK/flˈæməbəl/

Definitions

01catching fire easily

B2

adj. describes something that catches fire very easily and burns quickly.

adj. capable of being easily ignited and of burning quickly.

“Be careful with that liquid because it is highly flammable near a stove.”

“The safety inspector noted that the warehouse stored several highly flammable solvents without adequate ventilation or fire suppression systems.”

Usage

Often used with adverbs like 'highly', 'extremely', or 'potentially'.

Pitfall

The sign said 'unflammable' materials.

The sign said 'non-flammable' materials.

The opposite of flammable is 'non-flammable'. Note that 'inflammable' means the same thing as 'flammable', which can be confusing.

Synonyms

inflammablecombustible

Antonyms

non-flammablefireproof

03dangerous substances

C2

n. a substance or material that can catch fire easily.

n. any substance or material that is easily ignited.

“The truck was carrying flammables and had to follow a special route.”

“Regulations require that all flammables be stored in reinforced cabinets away from primary exit routes.”

Technical

Usage

Usually used in the plural form 'flammables' in industrial or safety contexts.

Synonyms

combustibleshazardous materials

Real-World Examples

“There's a lot homeowners can do to prepare for wildfires, such as managing flammable plants and using fire-resistant building materials.”
NPR · 17 Aug 2026
“Like oil lanterns, they were dangerous, primarily because they relied on an open flame and produced highly flammable acetylene gas.”
Ars Technica · 3 Aug 2026

Etymology

Back-formation from inflammable, which is used to avoid confusion with non-flammable, as the prefix in- is often used to mean "un-; non-", although it was originally meant in a sense closely related to en-.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

Related words

This entry

Level
B2 · Upper Intermediate
Frequency
Occasional
Updated

Scan code

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English Reference