improbable

IPA/ɪmˈprɒbəbl/
KK[ˌɪmprˈɑbəbəl]IPA/ɪmˈprɑːbəbl/

improbable — adjective

  • improbablepositive
  • more improbablecomparative
  • most improbablesuperlative

1. describing something that has only a small chance of happening, being real, or b

1.adjectiveB2
Definition

describing something that has only a small chance of happening, being real, or being true, so most people would not expect it.

Example

It is improbable that Lisa will finish the marathon in under three hours.

it is improbable that + clause

Karim told the police an improbable story about losing his keys in a river.

improbable + noun (story / tale / excuse)

Common collocations
  • highly improbable
  • seem improbable
  • an improbable story
  • an improbable pair
Synonyms
  • unlikely

    more common in everyday speech; 'improbable' is slightly more formal

  • doubtful

    focuses on uncertainty about truth; 'improbable' focuses on low likelihood

  • implausible

    stresses that something is hard to believe, not just unlikely to happen

Antonyms
  • likely

    everyday opposite — having a good chance of happening

  • probable

    direct formal opposite

Grammar Patterns

it is improbable that + clause

improbable + noun

Usage Note

Often used with 'highly', 'very', or 'quite' to strengthen the meaning. Stronger than 'unlikely' and slightly more formal; weaker and more neutral than 'impossible'.

Common Mistakes

It is improbable to rain tomorrow.
It is improbable that it will rain tomorrow.
'improbable' usually takes a that-clause, not a to-infinitive.

Word family

Synonym discussion

Sense: adjective/1

'Unlikely' is the everyday choice and the safest in spoken English: 'It is unlikely to rain.' 'Improbable' carries the same core idea but sounds slightly more formal and often appears in writing, news reports, and reasoned arguments: 'A second earthquake within the hour is improbable.' 'Doubtful' shifts the focus to the speaker's uncertainty about whether something is true or will succeed, rather than to a low statistical chance: 'It is doubtful whether the plan will work.' 'Implausible' is stronger again — it says a story or claim is so odd or poorly supported that listeners struggle to believe it: 'His alibi sounded implausible to the jury.' Use 'improbable' when the event is just unlikely; use 'implausible' when the claim is hard to swallow.

improbable ↗unlikely ↗doubtful ↗implausible ↗

Common collocations

Nouns

Adverbs

Phrases

  • it is improbable that
  • seem improbable
  • look improbable

Etymology

LatinFrenchEnglish

From Latin 'improbabilis', formed by adding the negative prefix 'im-' (a form of 'in-', meaning 'not') to 'probabilis' (worthy of approval, able to be proved). It reached English in the 1500s through French and at first meant 'not able to be proved'. The modern sense 'unlikely to happen or be true' grew from the same root idea: if something cannot be supported by evidence, people do not expect it to be the case.