What does improbable mean?
“Improbable” means very unlikely to happen, occur, or be true. It is stronger and more expressive than simply saying that something is “unlikely,” often suggesting that the event is so unexpected or extraordinary that it seems almost impossible. The word can also describe something striking because of its unusual appearance or effect, as in “an improbable beauty” or “an improbable combination of circumstances.” In formal and scientific writing, it may express a calculated assessment of rarity, while in conversation it frequently adds emphasis or wonder. “Improbable” is useful when discussing extraordinary outcomes, unusual circumstances, or results that contradict expectations. Although its meaning is broadly the same in British and American English, the pronunciation differs: British English usually has /ɒ/ in the stressed syllable, while American English has /ɑ/.
adjectiveNot likely to happen, occur, or be true; very unlikely. It can also describe something so unusual or unexpected that it seems remarkable.
- Not likely to happen, occur, or be true.
- So unusual, unexpected, or striking that it seems unlikely or remarkable.
"It seemed improbable that the small team would win the championship, but they did."
"The researchers calculated that such a result was statistically improbable."
"Against all expectations, the ordinary-looking building achieved an improbable beauty."
Improbable began as a simple negation: not probable. Over time, it came to suggest something not only unlikely but so unexpected that it captures the imagination.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does improbable come from?
“Improbable” was formed in English from the prefix “in-” meaning “not” and “probable,” giving it the original sense of “not probable.” It entered English in the early 17th century. Its deeper roots lie in Latin improbabilis, meaning “not believable” or “not likely,” which derives from “in-” and probabilis; the latter is related to probare, “to test, examine, or approve.” English words including “probable,” “probably,” and “probability” come from the same Latin root.
Related word forms
How improbable is actually used
In everyday use, “improbable” can convey a sense of striking or almost unbelievable unpredictability, especially for an event or outcome that nevertheless occurs. The pronunciation varies between British and American English, with the stressed vowel heard as /ɒ/ in British English and /ɑ/ in American English.
Easily confused with improbable
Probable means likely to happen or be true, whereas improbable means very unlikely to happen or be true.