flammable

flammable — adjective

1. A flammable material or substance can start to burn very quickly when it comes n

1.adjectiveB1
Definition

A flammable material or substance can start to burn very quickly when it comes near a flame or a high heat source.

Example

The warning label on the can says the paint inside is highly flammable.

typical warning label context on product packaging

Kofi checked that his workbench was clear of flammable chemicals before welding.

collocation: flammable chemicals; safety precaution context

Common collocations
  • highly flammable
  • extremely flammable
  • flammable liquids
  • flammable materials
  • flammable chemicals
  • flammable substances
  • flammable gases
  • flammable items
  • flammable objects
  • flammable goods
Synonyms
  • combustible

    A broader and more technical term — refers to anything that can catch fire and burn, not just things that ignite very easily

  • inflammable

    Has the exact same meaning as 'flammable' but is less common in modern safety labels because people mistakenly read it as 'not flammable'

  • ignitable

    More technical; refers specifically to the ability to catch fire rather than how fast something burns

Antonyms
  • non-flammable

    The direct everyday opposite — will not catch fire under normal conditions

  • fire-resistant

    Does not burn easily but may still catch fire under extreme heat; different from fully non-flammable

  • fireproof

    Stronger than non-flammable — implies it cannot burn even under very high heat

Usage Note

Often used in safety warnings, product labels, and fire-prevention instructions. The noun it describes is the material that burns, not the source of the flame.

Common Mistakes

The label says the liquid is inflammable, so it will not catch fire.
The label says the liquid is flammable, meaning it catches fire easily.
'Flammable' and 'inflammable' actually mean the same thing: both indicate something burns easily. The 'in-' prefix in 'inflammable' is not a negation here; it comes from Latin 'inflammare' (to set on fire).

Word family

  • flame
    nounA2
  • inflammable
    adjectiveC1
  • non-flammable
    adjectiveB1
  • flammability
    nounC1
  • inflame
    verbC1

Synonym discussion

Sense: adjective/1

All three words describe things that can catch fire, but they differ in usage and connotation. 'Flammable' is the most common term in everyday safety labels and warnings — it is the standard word on product packaging and in public safety messages. 'Combustible' is more technical and broader: it includes materials that can burn even if they do not ignite as easily as flammable ones. For example, a 'combustible material' may need a higher temperature to catch fire. 'Inflammable' has exactly the same meaning as 'flammable' but is confusing because the 'in-' prefix looks like a negation — many people wrongly believe it means 'not flammable'. For this reason, modern safety labels avoid 'inflammable' and use 'flammable' instead. If you see 'highly flammable' on a spray can, it means the contents catch fire extremely easily. If you see 'combustible' on a shipping document, it means the material can burn but may require more heat.

flammable ↗combustibleinflammable

Common collocations

Nouns

  • liquids
  • materials
  • chemicals
  • substances
  • gases
  • solvents
  • items
  • goods
  • objects
  • bushes
  • trees

Adverbs

Phrases

  • keep away from heat
  • store in a cool place
  • do not expose to flames

Etymology

LatinFrenchEnglish

The word 'flammable' was formed in English in the early 1800s from the Latin verb 'flammare' meaning 'to set on fire', which itself comes from 'flamma' meaning 'flame', combined with the English suffix '-able' meaning 'capable of'. Interestingly, the older word 'inflammable' existed first (from Latin 'inflammare' — 'to set on fire'), but safety officials created 'flammable' in the 20th century to avoid confusion: people kept misreading the 'in-' prefix as a negation, thinking 'inflammable' meant 'not flammable'. Today 'flammable' is the standard term for safety warnings worldwide.