What does improbability mean?
Improbability is a formal noun meaning the quality of being very unlikely or difficult to believe. It commonly describes the chances of an event, outcome, or situation, especially when the odds appear strongly against it: “the improbability of such a result.” The word is often more emphatic and more analytical than “unlikeliness,” and it can suggest that an event would require an exceptional combination of circumstances. Although “improbability” is usually uncountable when discussing the quality of something, count uses are also possible, as in “a series of improbabilities.” In everyday speech, people may simply say that something is unlikely, improbable, or against the odds, but “improbability” is especially useful in formal discussion of probability, chance, and surprising events.
The quality of being unlikely or improbable; a very small chance of something happening.
"Researchers were surprised by the improbability of the pattern appearing by chance."
This use is typically uncountable and is common in formal or analytical contexts.
An event or situation that is extremely unlikely to occur.
"The film unfolds through a series of improbabilities that strain credulity."
This count use is less common than the abstract, uncountable sense and often has a literary or narrative tone.
Used countably for individual unlikely events, situations, or results, especially in literary or analytical writing.
"The story depends on a sequence of improbabilities."
The word “improbability” captures the rare moment when an outcome is so unlikely that its occurrence feels almost unreal.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of improbability
The word is formed from the adjective “improbable” and the suffix “-ity,” a standard way of creating nouns from adjectives. “Improbable” comes through Latin from roots associated with “probable,” meaning likely or credible, while the “im-” prefix reverses that meaning. The English forms “probable,” “probably,” and “probability” belong to the same broad Latin etymological family.
How improbability is actually used
Usually uncountable when describing the quality of being unlikely, though “improbabilities” can be used countably for individual unlikely events or situations. It is formal and often conveys a stronger sense than “unlikeliness.”
Easily confused with improbability
No distinction is needed because the headword is itself “improbability”; use “improbability” when referring to the quality of being very unlikely or difficult to believe.